Best AI Models in October 2026: Frontier Models Compared

The best AI model in October 2026 depends on the work. GPT-6 Astra and Claude Fable 5.1 are the premium choices for difficult, long-running work. Claude Sonnet 5.5 is the practical daily driver. Grok 4.7 is the price-performance coding pick. Gemini 3.8 Flash is the fast multimodal option. GLM-5.3 Flash and DeepSeek Flash are budget candidates; prices differ by endpoint and billing route.

Model update: October 5, 2026. Claude Sonnet 5.5 (September 28) and GPT-6.1 Sol (September 29) are added from Anthropic's and OpenAI's documentation. Grok 4.7 pricing and named OpenRouter provider prices for DeepSeek V4 Flash, GLM-5.3, GLM-5.3 Flash, and Kimi K3 were rechecked against OpenRouter's public endpoint API. Earlier checks: GPT-6 Sol and Luna and Claude Opus 5.5 joined Teamday on September 23; other OpenRouter prices, DeepSeek direct pricing, and OpenAI Astra specifications were rechecked on September 17. Other release details retain their September 5 verification date; older pricing checks are marked below. Prices are per one million tokens and the route is identified where gateway and direct API quotes differ. Cache writes, tools, long-context tiers, time-of-day overrides, and taxes can change the total. Recommendations are starting points, not an independent benchmark ranking.

Best AI Models: Quick Picks

October 2026 Frontier Model Comparison

Context size is not the same as usable memory. A model may accept one million tokens yet lose accuracy across a noisy history. Long-context price tiers, caching, compaction, and the agent harness often matter more than the headline window.

How We Chose the Models

This is not a single-score leaderboard. We compare:

• official release status and exact API model IDs;
• capability for coding, research, tool use, computer use, and knowledge work;
• input and output limits;
• direct list price and cache economics;
• open-weight availability and license;
• whether the model can be used in a durable agent harness;
• deprecations and regional access restrictions.

Provider benchmarks are useful evidence, but they are not interchangeable. A score can change with the harness, tool set, reasoning budget, retry policy, test subset, and grader. We use them to understand a model's intended strengths, not to manufacture a false universal ranking.

1. OpenAI GPT-6 Astra, Sol, and Luna

OpenAI rolled out GPT-6 Astra (gpt-6-astra) from September 3. It is OpenAI's most capable model for the hardest reasoning, coding, computer-use, and research work.

Astra takes text and image input, has an April 30, 2026 knowledge cutoff, and supports reasoning effort from low through medium, high, and xhigh to max. Unlike GPT-5.6, Astra does not support the "none" effort tier. Batch and Flex processing cost 50% of list; Fast mode costs 2x. Requests above 272K input tokens bill at $20 / $2 / $25 / $75, so dumping a whole workspace into every call is still poor architecture.

GPT-6.1 Sol (gpt-6.1-sol) followed on September 29. OpenAI describes it as near-Astra performance for complex coding, computer use, and professional work at a lower cost. Prompts up to 272K input tokens cost $2 input, $0.10 cached input, $2.50 cache write, and $10 output, which halves GPT-6 Sol's cached-input rate. It takes text and image input, and multi-agent delegation is in beta.

Two facts matter for budgeting. First, Astra costs 5x GPT-6 Sol, so Sol and Luna are lower-cost choices for routine work. Second, OpenAI bills prompt-cache writes at 1.25x the input price on every tier. Any estimate that assumes "no cache-write fee" is wrong.

OpenAI retired GPT-5.4 from Codex on August 31, 2026.

Direct API and gateway quotes can differ: the September 17 OpenRouter snapshot lists openai/gpt-5.6-sol at $2 input / $10 output, while the direct API comparison above uses $4 / $20. Check the billing route you will actually use.

Sources: GPT-6 Astra specifications, GPT-6.1 Sol, OpenAI changelog, GPT-6 Sol, GPT-6 Luna, OpenAI API pricing, OpenRouter model API.

2. Anthropic Claude: Fable 5.1, Opus 5.5, Sonnet 5.5, and Haiku 4.5

Anthropic now has four current choices.

Claude Fable 5.1 (claude-fable-5-1) shipped on September 1 as the successor to Fable 5 in the same tier at the same base price: $10 input and $50 output, with a 1M-token context and up to 128K output tokens. The practical improvement is cache economics — cache reads cost $0.25 per million tokens, four times cheaper than Fable 5's $1. Fable 5 stays callable as a legacy model.

Claude Opus 5.5 succeeds Opus 5 at $4 input and $20 output. Anthropic recommends it as a starting point for most work, including complex coding and long-running agents. Opus 5 remains a legacy model.

Claude Sonnet 5.5 (claude-sonnet-5-5) launched on September 28 at $2 input and $10 output, with a 1M-token context and up to 128K output tokens. Anthropic describes it as the best combination of speed and intelligence in its lineup. Code written for Sonnet 5 can break on 5.5: Anthropic lists five changes, including forced tool use (tool_choice of any or tool) returning an error and a different way to turn off up-front thinking. Test before switching a pinned integration. Sonnet 5 no longer appears in Anthropic's current-model lineup; OpenRouter still listed it at $2 / $10 on October 5. On September 30, Anthropic also announced that Claude Sonnet 4.5 retires from the Claude API on November 30, 2026.

Claude Haiku 4.5 remains the fastest and cheapest Claude at $1 input and $5 output with a 200K context. Anthropic has set October 15, 2026 as the earliest retirement date, so plan a migration path for anything pinned to it.

Sources: Claude models overview, Claude release notes, Claude Fable 5.1 on Teamday, Claude Opus 5.5 on Teamday.

3. Google Gemini 3.8 Flash and Gemini 3.1 Pro

Google's Flash line moved fast this summer: Gemini 3.6 Flash on July 21, Gemini 3.7 Flash on August 13, and Gemini 3.8 Flash (gemini-3.8-flash) generally available on September 2.

Gemini 3.8 Flash is Google's most intelligent Flash model, built for long-horizon software engineering and autonomous agents, with a 1M-token context. It costs $0.75 input, $0.075 cached, and $3.75 output — the same 50% promotional price as 3.7 Flash. The promotion runs through December 31, 2026; the price doubles on January 1, 2027. Google keeps 3.7 Flash available for compute-efficient workflows. A gated Gemini 3.8 Flash Cyber variant exists for vulnerability work.

Gemini 3.5 Flash still lists at $1.50 input, $0.15 cached, and $9 output — double the newer Flash models — and has left Google Antigravity's model selector. There is no reason to start new work on it.

Gemini 3.1 Pro remains the Pro-tier option while Google's flagship Pro successor is still unshipped. Its price is tiered: $2 input and $12 output up to 200K tokens, then $4 and $18 above that.

For production, stable model IDs matter. Use Google's deprecation table before pinning any preview alias.

Sources: Gemini API pricing, Gemini model lifecycle, Gemini models.

4. xAI Grok 4.7 and Grok 4.6

xAI released Grok 4.6 on August 12 as its recommended model. It has a 500K-token context window and costs $2 input, $0.50 cached input, and $6 output. Prices double above 200K tokens of context, so keep prompts under that line where you can.

Grok 4.6 replaces Grok 4.5 ($2 / $0.30 cached / $6) as the recommended pick at the same headline price. Grok 4.3 is the budget tier at $1.25 / $0.20 / $2.50 with a 1M context, and Grok Build 0.1 ($1 / $0.20 / $2) is the coding-agent model behind the Grok Build CLI.

Grok 4.7 reached the xAI API on September 21 as grok-4.7, which xAI describes as its frontier model for coding, agentic tasks, and knowledge work. It has a 500K-token context and text and image input. It costs $2 input, $0.50 cached, and $6 output below 200K prompt tokens, and $4 / $1 / $12 above. OpenRouter listed x-ai/grok-4.7 at the same $2 / $6 on October 5, replacing the $1.60 / $4.80 quote it showed in September. Teamday's Grok Build harness still runs Grok 4.6.

Sources: xAI models and pricing, xAI release notes, OpenRouter model API.

5. DeepSeek V4 Pro and V4.1 Flash

V4.1 Flash arrived on September 10 with image input. DeepSeek's direct API now uses deepseek-flash; the older deepseek-v4-flash and deepseek-v4-flash-vision-exp names route to V4.1 Flash. V4 Pro 0813 remains available.

Peak periods are weekdays 01:00–04:00 and 06:00–10:00 UTC. Both models have a 1M context. Sources: DeepSeek pricing, September 10 release.

On OpenRouter, deepseek/deepseek-v4-flash and deepseek/deepseek-v4.1-flash are served by many third-party providers at very different prices. On October 5, DeepInfra charged $0.09 / $0.18 for V4 Flash, while the route with the lowest input price charged $0.03 input but $1.28 output. OpenRouter's catalog-level quote changes as providers join, so compare per-provider endpoint prices for your input/output mix. The earlier claim that the Pro gateway price was always the off-peak rate was incorrect. Use the exact route and its current billing rules. Source: OpenRouter model API.

6. Z.ai GLM-5.3 and GLM-5.3 Flash

Z.ai released GLM-5.3 on August 18 as the successor to GLM-5.2, with a long context. On October 5 most of its OpenRouter endpoints reported 1,048,576 context tokens. Z.ai's own endpoint there charged $1.40 input and $4.40 output; third-party providers ranged from $0.03 input with $12 output to $2.80 / $8.80.

GLM-5.3 Flash is the lower-priced multimodal option. On October 5 most of its OpenRouter endpoints reported 1,048,576 context tokens, and DeepInfra charged $0.075 input and $0.25 output for z-ai/glm-5.3-flash, a 50% promotional discount that can end without notice; Z.ai's own endpoint charged $0.15 / $0.50. Other providers trade a lower input price for a higher output price, so price the route against your own input/output mix. These quotes establish price, not performance or availability. See the live catalog before choosing a route.

Sources: Z.ai documentation, GLM-5.3 on OpenRouter, GLM-5.3 Flash on OpenRouter.

7. Qwen3.8-Max, Qwen3.8-Flash, and Qwen 3.7 Plus

Alibaba's Qwen line now has three tiers that matter, and the billing plan you hold decides which you can use.

Qwen3.8-Max (August 3) is the premium tier: 1M-token context, $2 input and $6 output. Qwen3.8-Flash (August 26) is the efficient tier: 125B parameters, open weights, text, image, and video input, 1M context, 131K max output, at $0.15 input and $0.47 output. Both are Token Plan (API key) models only — neither is included in the $50 Coding Plan.

Qwen 3.7 Plus remains the Coding Plan flagship at $0.40 input and $1.60 output with a 256K context. If you pay for the Coding Plan, this is still your model.

Alibaba also published Qwen3.8-Flash-Next on August 28, an experimental preview of the architecture behind Qwen 4. Qwen 4 itself has no announced date. Use a dated snapshot for production when provider aliases can move.

Sources: Alibaba Model Studio model list, Alibaba model pricing, Qwen3.8-Flash on Teamday.

8. Kimi K3, Kimi K2.7 Code, MiniMax M3, and Mistral

Kimi K3 (July 16) is Moonshot AI's frontier reasoning model: 2.8 trillion total parameters and a 1M-token context. It costs $3 input, $0.30 cached, and $15 output through Vercel AI Gateway or Moonshot AI's OpenRouter endpoint, or draws on a Kimi for Coding plan. It is the pick when you want a non-US-lab frontier model for long-context reasoning.

Kimi K2.7 Code is the coding-focused open-weight mixture-of-experts model below K3: 262K context, multimodal input, $0.95 input and $4 output. It is designed for long agent trajectories rather than short code completion. See the official Kimi K2.7 Code model card.

MiniMax M3 is open weight, natively multimodal, and supports up to one-million-token context, with a guaranteed minimum of 512K depending on the route. Its direct price up to 512K was $0.30 input and $1.20 output when last checked in July. See MiniMax M3.

Mistral Medium 3.5 is the current general frontier tier at $1.50 input and $7.50 output. Mistral Small 4 is Apache 2.0, multimodal, 256K context, and only $0.15 input and $0.60 output. Mistral Large 3 remains a major open-weight model but is no longer the newest Mistral default. Mistral prices were last checked in July. See Mistral Medium 3.5 and Mistral Small 4.

9. Meta Llama 4

Meta has not published a newer general-purpose Llama release than Llama 4 Scout and Maverick, released April 5, 2025.

That makes Llama 4 old by frontier-model standards, but not irrelevant. Scout's 10M headline context and ability to fit on one H100 with Int4 quantization remain useful. Maverick offers a larger 128-expert architecture. More importantly, the Llama ecosystem has broad hosting, fine-tuning, and deployment support.

Do not describe Llama 4 Behemoth as released. Meta previewed it as a teacher model that was still training.

Source: Meta's Llama 4 announcement.

What You Can Use in Teamday Today

Teamday does not claim that every model in this comparison is a one-click option. As of September 30, the first-class routes in the model picker are:

Saved agents keep their model. When a model retires from the picker, Teamday maps it to the same tier — Fable 5 to Fable 5.1, GLM-5.2 to GLM-5.3, Gemini 3.5 Flash to Gemini 3.8 Flash — so nothing moves to a pricier tier on its own.

That means you can select a current frontier model for an AI employee, give the underlying agent workspace context and tools, and let it produce durable work rather than a disposable chat answer. Browse AI employees, compare agent harnesses, or see finished work.

The exact model matters, but the harness decides whether the model can inspect files, use tools, recover from failure, run for more than one turn, and leave an auditable result.

How to Choose a Model for Real Work

Use this five-part test:

1. Define the accepted output. A merged code change, reviewed research memo, updated forecast, or campaign package is testable. “Be smart” is not.
2. Run the same job on two models. Keep tools, context, and acceptance criteria constant.
3. Measure total task cost. Include output tokens, cache writes, retries, failed tool calls, and human review.
4. Test long-horizon reliability. Many models are excellent for five minutes and fragile after fifty tool calls.
5. Pin the model and record the date. Preview aliases and gateway routes change.

For most companies, the winning architecture is tiered:

• a fast, inexpensive model for routing, extraction, and drafts — GPT-5.6 Luna, Gemini 3.8 Flash, or GLM-5.3 Flash;
• a strong daily model for most agent work — Claude Sonnet 5.5, Grok 4.7, or GPT-5.6 Terra;
• a premium model for difficult or high-consequence tasks — GPT-6 Astra, Claude Fable 5.1, or Claude Opus 5.5;
• an open or alternative provider path, such as the OpenRouter free models, for cost control and resilience.

What Changed Since September 23

• Anthropic: Claude Sonnet 5.5 launched on September 28 at Sonnet 5's $2 / $10. Claude Sonnet 4.5 retires from the Claude API on November 30, 2026.
• OpenAI: GPT-6.1 Sol arrived on September 29 at $2 / $10 with $0.10 cached input.
• xAI: Grok 4.7 is on the xAI API at $2 / $6 below 200K tokens. OpenRouter now lists the same price, up from $1.60 / $4.80.
• Gateways: new low-input providers on OpenRouter changed the catalog-level quotes for DeepSeek V4 Flash, GLM-5.3, and Kimi K3, so this guide now names the provider behind each gateway price. Most GLM-5.3 and GLM-5.3 Flash endpoints report 1,048,576 context tokens.
• Google and DeepSeek: no new text model since Gemini 3.8 Flash (September 2) and DeepSeek V4.1 Flash (September 10). Google's September 22 releases were text-to-speech models.

What Changed Since July 2026

The July version of this article was current for about six weeks. The September refresh records the real changes:

• OpenAI: GPT-6 Astra (September 3) replaced GPT-5.6 Sol as the top model at 2.5x the price. OpenAI cut GPT-5.6 prices over the summer (Sol $4 / $20 through November 21; Terra $2 / $12; Luna $0.20 / $1.20) and retired GPT-5.4 from Codex on August 31. Cache writes cost 1.25x input on every tier — the earlier "no cache-write fee" claim was wrong.
• Anthropic: Claude Fable 5.1 (September 1) succeeded Fable 5 at the same price with cache reads four times cheaper. Sonnet 5's $2 / $10 launch price became permanent. Haiku 4.5 has an October 15 retirement floor.
• Google: three Flash releases in six weeks — 3.6 (July 21), 3.7 (August 13), 3.8 (September 2) — all at $0.75 / $3.75. Gemini 3.5 Flash left the Antigravity selector. The Pro successor still has not shipped.
• xAI: Grok 4.6 (August 12) replaced Grok 4.5 as the recommended model at the same $2 / $6. Grok 4.7 followed on September 21.
• DeepSeek: V4.1 Flash arrived September 10 and replaced the older Flash models on the direct API. Peak and off-peak billing remain; gateway model IDs and prices must be checked separately.
• Z.ai: the September 23 OpenRouter quote for GLM-5.3 Flash was $0.15 / $0.50, and for GLM-5.3 $0.84 / $2.64, both with 1,310,720 context tokens. The earlier promotion and cheapest-model claim have been corrected.
• Alibaba: Qwen3.8-Max (August 3) and Qwen3.8-Flash (August 26) arrived above and below Qwen 3.7 Plus, but only for Token Plan customers.
• Moonshot: Kimi K3 (July 16) arrived above Kimi K2.7 Code as a 1M-context frontier reasoning model.

The durable lesson is unchanged: never turn a rumor into a row in a comparison table, and never let a price table go two months without a check.

Frequently Asked Questions

What is the best AI model in October 2026?

There is no universal winner. GPT-6 Astra and Claude Fable 5.1 are the top choices for the hardest long-horizon work; Claude Sonnet 5.5 is the practical daily driver; Grok 4.7 is the price-performance coding pick; Gemini 3.8 Flash is the fast multimodal option; and GLM-5.3 Flash and DeepSeek Flash are budget candidates whose prices depend on the endpoint and billing route.

What is the newest OpenAI model in October 2026?

GPT-6.1 Sol (September 29) is OpenAI's newest model: near-Astra performance for complex coding and professional work at $2 input, $0.10 cached input, and $10 output per million tokens. GPT-6 Sol and Luna arrived on September 22, after GPT-6 Astra on September 3. Astra remains the most capable model; Luna costs $0.10 / $0.50 on the direct API. GPT-5.6 Sol, Terra, and Luna remain available.

Which AI model is cheapest in October 2026?

Budget-model prices depend on the provider route. On October 5, DeepInfra's OpenRouter endpoints charged $0.09 / $0.18 per million tokens for DeepSeek V4 Flash and a 50%-off promotional $0.075 / $0.25 for GLM-5.3 Flash (Z.ai's own endpoint: $0.15 / $0.50), while some routes with lower input prices charged far more for output. GPT-6 Luna costs $0.10 / $0.50 on OpenAI's direct API. The direct DeepSeek Flash API serves V4.1 Flash at $0.30 / $1.20 peak or $0.15 / $0.60 off-peak. Compare total task cost and actual endpoint availability.

Which current AI models are open weight?

Important current open-weight options include DeepSeek V4, GLM-5.3 Flash (MIT), Qwen3.8-Flash, Kimi K2.7 Code, MiniMax M3, Mistral Large 3 and Small 4, and Meta Llama 4. Licenses differ, so open weight does not always mean unrestricted open source.

Can I use these AI models in Teamday?

Teamday's model picker directly exposes GPT-6 Astra, GPT-6.1 Sol, GPT-6 Sol and Luna plus GPT-5.6, Claude Fable 5.1, Opus 5.5, Sonnet 5.5 and Haiku 4.5, Gemini 3.8 Flash, 3.7 Flash and 3.1 Pro, Grok 4.6, Qwen 3.8 Max, 3.8 Flash and 3.7 Plus, Kimi K3 and K2.7 Code, GLM-5.3 and GLM-5.3 Flash, and DeepSeek V4 Pro and Flash. MiniMax, Mistral, and Llama are not first-class picks.

Related Model Guides

• Best AI image models in 2026
• Best AI video models in 2026
• Best AI voice models in 2026
• Top AI models on OpenRouter
• OpenRouter free models
• AI API pricing comparison

Next scheduled verification: November 2026, or sooner after a major provider release or pricing change.