Claude Fable 5 is back. After an 18-day suspension under a US export-control order, Anthropic's most capable model returned globally on July 1 — in the same week it made the cheaper Claude Sonnet 5 its new default. That one-two punch is a good excuse to answer the question everyone's actually asking: what AI model should you use? In 2026, every lab now ships a full family of models instead of one flagship, and you can dial reasoning "effort" up or down on top of that — so the real answer isn't a brand, it's a system for choosing.