We compared the top model from each family by net improvement score and median cost per task. Family is defined as variants within the same model base name.

GPT-6 Astra and Claude Fable 5.1 stand out: both cost far more than other models from their respective labs despite relatively close performance.

By @OpenAI: • GPT-6 Astra (Max): +11.7% | $3.94/task • GPT-5.6 Sol (xHigh): +7.0% | $1.03/task

By @AnthropicAI: • Claude Fable 5.1 (Max): +13.7% | $4.40/task • Claude Opus 5 (High): +10.2% | $2.07/task