GPT-6 Astra is OpenAI's September 2026 flagship—very capable at finishing messy, multi-step assistant work. Our tests put it #2 overall, with helpfulness, instruction following, and comprehension at or near the top of the board. Writing and output quality are the gap versus Claude Fable 5.1: prose is competent and on-brief, but less voiced and less literary. A strong pick when you want a capable general assistant and can live without Fable's writing.