Mostly Gemini 2.5 Pro lately.
I get asked this often enough that I have a FAQ entry with automatically updating statistics [0].
Model Tokens Pct Gemini 2.5 Pro 4,027,983 88.1% Sonnet 3.7 518,708 11.3% gpt-4.1-mini 11,775 0.3% gpt-4.1 10,687 0.2%