I use “all of them”. My primary harness is oh-my-pi. I probably use 10 different models on a regular basis.

I occasionally use OpenCode.

I try to use Codex and Antigravity as much as I can, often using it as a secondary agent (due to different usage pricing models than API). The same skills and MCPs work across harnesses.

Edit: I don’t use Claude Code simply because I already have enough to deal with and don’t see a major advantage to their harness. I use Opus credits from my Google subscription on the rare occasion I need them.

Cursor is also worth checking out particularly at the $20 a month price tier. If you have Grok you effectively already have it too.

I expect to have a completely different answer a year from now. The main “lift” we’ve gotten from AI tools is our clients now get an Android + iOS app + macOS app + Electron + PWA to go with whatever web based app they want us to build, at essentially the same original price. (There’s also a CLI and a TUI, but so far none of them care about that…)

We just made the decision to start adding MCPs to apps. Gonna be an interesting conversation in a few weeks when I can tell my business contact he can use his favourite chatbot to now plug in directly to the custom app he bought from me.