GPT-6 vs Claude Opus 5.5 vs Gemini 3.1 Pro: Best AI Model Right Now

The best AI model right now depends on the job: Claude Opus 5.5 is the strongest pick for coding, writing and long professional documents, GPT-6 Astra leads on science, agents and computer use, and Gemini 3.1 Pro is the cheapest of the three for heavy API work and the best value inside Google’s apps. If you just want one subscription, ChatGPT Plus and Claude Pro both cost $20 a month and are close enough that your daily tasks should decide.

This guide compares the best AI model from each lab as of 10 October 2026, using the vendors’ own published numbers, real plan prices and API rates. We also cover Gemini 4 Argon, which Google announced on 30 September 2026 but which almost nobody can use yet.

Quick answer: which is the best AI model right now?

Here is the short version. Pick the row that matches what you do most.

If you want the background on OpenAI’s three model sizes first, read our explainer on GPT-6 Astra vs Sol vs Luna, because the name “GPT-6” covers several models with very different prices.

Meet the contenders

GPT-6 Astra (OpenAI)

GPT-6 Astra is OpenAI’s flagship. OpenAI calls it “the world’s most intelligent and aligned model” on its GPT-6 Astra launch page. It has a 1,050,000-token context window and up to 128,000 output tokens. In ChatGPT, Astra powers GPT-6 Pro on the Pro, Business and Enterprise plans and runs inside ChatGPT Work and Codex on Plus and above.

The everyday ChatGPT chat model is different. Since 7 October 2026, paid plans chat with GPT-6 Sol and Free and Go users get GPT-6 Luna, both with the new Intelligent UI that answers with charts, buttons and small tools. Our guide to ChatGPT Intelligent UI shows what that looks like.

Claude Opus 5.5 (Anthropic)

Claude Opus 5.5 launched on 22 September 2026 and is the default model in Claude Code on paid plans. It has a 1M-token context window, 128K max output and costs $4 in and $20 out per million tokens on the API, down from $5 and $25 for Opus 5. Anthropic says it costs about 40% less to run than Opus 5 on typical workloads. It always thinks before answering; you cannot switch thinking off.

Gemini 3.1 Pro (Google)

Gemini 3.1 Pro is Google’s only generally available Pro model, and it is still labeled preview in the API. Free Gemini users get “varying access to 3.1 Pro”, while Google AI Pro subscribers get higher access, a 1M-token context window and Gemini inside Gmail, Docs and Vids. It is the oldest of the three flagships here, which shows on the newest benchmarks.

Waiting in the wings: Gemini 4 Argon

Google’s Gemini 4 Argon announcement describes a frontier model for coding, enterprise work and cyber defense. As of 10 October 2026 it is rolling out only to trusted defenders in Google’s Fairwind Program. Paid API customers and Google AI Ultra subscribers come next, with no date. We cover it in detail in our Gemini 4 Argon guide, but you cannot build on it today.

Benchmarks: what the vendors claim

Benchmarks are standardized tests. Each lab picks the ones that flatter it, runs them at different effort settings, and sometimes reports a rival’s score as published by that rival. Read this table as “who claims what”, not as an independent lab test.

Sources: Anthropic’s Opus 5.5 page (max effort), OpenAI’s Astra page and Google’s Argon post. We did not find Gemini 3.1 Pro scores on these newer tests in the sources we checked, so it is left out of the table rather than guessed.

The pattern is still useful. Opus 5.5 leads on coding and office work, Astra leads on science and edges ahead on automation, and Argon claims the top automation and long-coding scores but is not available. Anthropic also says Opus 5.5 at default effort matches Astra on Terminal-Bench 4.0 for about 40% of the cost, which matters more than the raw score if you pay per token.

Coding: Claude Opus 5.5 leads, Astra is close

For developers, Opus 5.5 is the model to beat. It tops Terminal-Bench 4.0 and FrontierCode in Anthropic’s table, and it comes bundled with Claude Code on every paid Claude plan, sharing one usage pool with chat. GPT-6 Astra runs inside Codex on ChatGPT Plus and above, where OpenAI estimates 5 to 45 Astra messages per 5-hour window on Plus.

Gemini 3.1 Pro is usable for coding through Google’s Jules agent and Antigravity on AI Pro, but on the newest agentic tests it is not in the same class as the two newer models. If you want tool-by-tool advice, our best AI coding assistants list and the Claude Code vs Cursor comparison go deeper.

Writing, research and long documents

All three handle about a million tokens of context in their top configurations, which is several long reports at once. Our context window explainer explains what that means in practice. The difference is in output quality and limits.

• Claude Opus 5.5 has the highest GDPval-AA office-work score and, in our everyday use, writes long drafts that need the fewest edits. It is our pick for reports, proposals and editing.
• GPT-6 Astra and Sol are excellent researchers. Astra posts strong browsing (BrowseComp 91.5%) and long-context retrieval scores, and ChatGPT’s deep research and Intelligent UI make answers easy to scan.
• Gemini 3.1 Pro shines when your documents already live in Google Drive, because Gemini reads them in Docs and Gmail without uploads. Gemini Notebook (formerly NotebookLM) is a strong free study tool on top.

For a head-to-head on writing only, see our ChatGPT vs Claude comparison and the Claude vs Gemini guide.

Pricing compared: apps and API

Consumer plans

The key detail: $20 on ChatGPT Plus does not buy you unlimited Astra in chat, while $20 on Claude Pro does include Opus 5.5, within a five-hour limit of roughly 45 short messages. Full plan details are in our ChatGPT pricing guide, Claude pricing guide and Gemini pricing guide.

API prices per million tokens

A worked example: a job with 2 million input tokens and 500,000 output tokens costs $20 + $25 = $45 on Astra, $8 + $10 = $18 on Opus 5.5, and $4 + $6 = $10 on Gemini 3.1 Pro. Watch the long-prompt rules too. OpenAI bills the whole request at 2x input and 1.5x output above 272K input tokens, and Gemini 3.1 Pro rises to $4 and $18 above 200K. Claude 4.6 and later models have no long-context surcharge. See our guides to OpenAI API pricing, Claude API pricing and Gemini API pricing for every model.

Limits, privacy and access

• Usage caps. GPT-6 Pro “does not include unlimited use”; Pro $200 gets 200 GPT-6 Pro messages a week. Claude limits reset every five hours with weekly caps on top. Google describes AI Pro as 4x the Free plan’s limits.
• Training on your data. ChatGPT Business, Enterprise and Edu content is not used for training by default, and consumer users can switch it off in Data controls. Claude consumer users choose whether chats train models; Team, Enterprise and API are excluded. Opus 5.5 is available with zero data retention on the API.
• Safety routing. Opus 5.5 reroutes most cybersecurity tasks to Opus 4.8 unless you are verified. Argon’s unguarded cyber abilities are why Google is releasing it so slowly.
• India. ChatGPT accepts UPI for Go and Plus. Google AI Pro is Rs 1,950 a month. Claude introduced rupee pricing in July 2026, reported at about Rs 2,000 for Pro.

Choose GPT-6, Claude or Gemini

Choose GPT-6 (ChatGPT) if

• You want one app for chat, images, voice, research and agents, with interactive Intelligent UI answers.
• Your work leans on science, math or long autonomous tasks in ChatGPT Work.

Choose Claude Opus 5.5 if

• You code, write or edit long documents most of the day.
• You pay per token and want flagship quality at less than half of Astra’s price.

Choose Gemini 3.1 Pro if

• You live in Gmail, Docs and Drive, or want storage and YouTube Premium Lite bundled in.
• You run high-volume API jobs where price beats peak quality, or you want early Argon access on Ultra.

Still undecided on the chat apps themselves? Our ChatGPT vs Gemini comparison covers features beyond the model.

Frequently asked questions

Our verdict: the best AI model for most people

If you code or write for a living, Claude Opus 5.5 is the best AI model right now: it leads the coding and office-work benchmarks its maker published, it is cheaper per token than GPT-6 Astra, and Claude Pro puts it in your hands for $20 a month. If you want the broadest assistant with the best science and agent performance, GPT-6 in ChatGPT Plus is the safer all-rounder. Gemini 3.1 Pro is the value pick for Google Workspace users and budget API builders, and Gemini 4 Argon is one to watch once Google opens it up. Prices and model access change often, so confirm current plans on each vendor’s pricing page before you subscribe.