GPT-6 vs Claude 5.5 vs Gemini 4: Which AI Is Better?

OpenAI presents GPT-6 Astra as its highest-capability flagship and GPT-6.1 Sol as a cheaper option for demanding work. Anthropic markets Claude Opus 5.5 for high-complexity tasks and Sonnet 5.5 for a more economical mix of design, documents and programming. Google presents Gemini 4 Argon as a frontier model in coding, knowledge work and multimodal understanding; access restrictions apply at launch. The fair comparison is a specific model variant, thinking level, tool access and deployment date, not one company's marketing label against another company's whole product family.

A team building software agents can trial Astra, Opus and Sonnet with identical GitHub issues and a fixed tool budget. An analyst can compare how each model cites evidence, extracts fields from long PDFs and admits uncertainty when sources conflict. For marketing copy, consistency with brand instructions and revision count may matter more than abstract reasoning scores. If a provider offers integrated workspace permissions, audit features or regional hosting, that can outweigh a modest evaluation difference. Gemini's broader availability should be checked before presenting Argon as a choice any buyer can activate today.

Artificial Analysis tests composite problem-solving ability under defined configurations, while Arena captures comparative user preference; these evaluate different outcomes. Published figures also change when datasets, judge models and model versions change. A convincing proof-of-concept tracks task success, retries, time to correct an error, token cost and human review. Do not claim that a particular model 'hallucinates the least' without a consistent independently checked study. RecoupRev's view: test at least two different labs on the work you actually intend to delegate, especially when errors can move money or affect customers.