GPT-6.1 Sol vs Claude Opus 5.5 vs Gemini 4 Argon: Frontier Models Compared
OpenAI, Anthropic and Google each shipped a frontier model within eight days. Prices, access and best uses, from the vendors' own launch pages.
Late September 2026 put three new frontier models on the market within eight days: Anthropic's Claude Opus 5.5 (September 22), OpenAI's GPT-6.1 Sol (September 29) and Google's Gemini 4 Argon (September 30). Each vendor publishes its own benchmarks, so this comparison sticks to what you can check: price, access and the work each was built for.
Side by side
| GPT-6.1 Sol | Claude Opus 5.5 | Gemini 4 Argon | |
|---|---|---|---|
| API input / output per 1M tokens | $2 / $10 | $4 / $20 | $2 / $10 introductory, then $4 / $20 |
| Cached input per 1M | $0.10 | $0.20 | 95% off input |
| Consumer access | ChatGPT Plus, Pro, Business, Enterprise, Edu (Work and Codex) | Claude Pro, Max, Team, Enterprise | Google AI Ultra |
| Built for | Agentic coding, computer use, professional work at low cost | Agentic coding, computer use, knowledge work | Long coding, legal and finance work, cyber defense |
Which one to pick
- Lowest cost for agent work: GPT-6.1 Sol, especially with heavy context reuse at $0.10 per million cached tokens.
- Already living in Claude Code: Opus 5.5, with Sonnet 5.5 at half the price for routine sessions.
- Deep in Google's tools or doing security work: Argon, if you have Google AI Ultra or API billing.
- Not sure: use an editor that lets you switch models per task.
One subscription, several models
Cursor Pro+ ($399.99 for a year, or the one-month Pro+ with Grok Bot) runs OpenAI, Claude and Gemini models from one plan, so you can try each on your own code. For pay-as-you-go use in Claude Code or Codex CLI, see the Claude API credit and Codex API packs.
Frequently asked questions
Which is the smartest?
Each vendor's benchmarks favour its own model. Try the same real task on two of them before committing to a plan.
Is GPT-6 Astra missing from this table?
Astra is OpenAI's higher tier at $10 in and $50 out. See Astra vs Sol vs Luna.
Related guides
- Claude Opus 5.5 vs Sonnet 5.5 vs Haiku 5.5: Which Claude to Use
- Gemini 4 Argon Explained: Google's New Frontier Model and Who Gets It
- AI Coding Agents Compared (October 2026): Codex, Claude Code, Cursor, Factory, Muse Code
- Linear Business: Unlimited Teams, Insights, and a 1-Year Coupon
- Bolt.new Pro: 10M Tokens a Month, Custom Domains, and a 1-Year Coupon
- Railway Hobby Coupon: $5 of Usage a Month and What Bills Extra