GPT-6 Astra vs GPT-6.1 Sol vs Gemini 4 Argon vs Claude Fable 5.1: Which Frontier Model Fits Which Job

Anthropic, OpenAI and Google DeepMind released four frontier models within 30 days, with overlapping benchmark scores but divergent pricing. OpenAI cancelled GPT-6.1 Astra on September 28 after it failed internal scope and authorization tests. GPT-6.1 Sol matches GPT-6 Astra on DeepSWE v1.1 at one-fifth the cost. Claude Fable 5.1 costs $9.18 per task versus $4.72 for GPT-6 Astra at identical list prices. Gemini 4 Argon is available only through Google's Fairwind program.