GPT-6 Astra and Claude Fable 5.1 came out within a few days of each other, and the "which one is better" posts started almost immediately. I collected the main numbers in the chart above. Honestly, they're closer than I expected. They score the same on the Artificial Analysis Intelligence Index, cost the same per token, and both handle a 1M-token context. Astra gets through tasks for a lot less money and seems stronger at terminal work and automation. Fable 5.1 looks better on long-running projects and big codebases. The more I looked at it, the less it felt like a competition. Their strengths don't overlap much, so I started wondering if the smarter move is to just use both. Let Astra build something, then have Fable 5.1 review it. Or the other way around. But I'm not sure that works out in practice. Two models means two sets of prompts to maintain, two APIs to deal with, and two bills. And when something goes wrong, it's harder to tell where the problem came from. So I'm curious what you think. If you were starting a serious project today, would you pick one model and really get to know it, or use both and let them cover each other's weak spots? If you've already tried either of them, or both, I'd love to hear how it went.