I am mostly using Gemini, but that's a decision I made 2-3 months ago. I try my best not to hint at what answer I am hoping for/would benefit me, and I play devil's advocate as much as possible.

For now, I'd say Claude. I tried to work with other LLMs such as Gemini, Codex, GPT and Grok(high versions), but still Claude (4.8) gave me the best outcome.