I use Fable for writing code and some planning. I use GPT for planning/roadmaps and code review, it checks Fable. I use Gemini for stray conversations. Gemini has a better conversational style than GPT, less robotic; it hallucinates more unfortunately, it has plainly fallen quite a bit behind, but it's still highly useful to converse with, research with, etc. And it spares me wasting usage of GPT or Fable. I use Gemini for the 'everything else' category, basically. Gemini never goes anywhere near anything serious.

Fable & Claude Opus 4.x or 5 are terrible to talk to about anything. I gave up on that entirely and just use Anthropic's models for work.

Any less serious technical work I'll use GPT for, as the usage limits are quite fantastic.