I've tested ChatGPT Sol 6.1 Medium, Argon4 Medium and Claude Opus 5.5 in Claude desktop app.
If I would make a tierlist in regards how those feels when working with them with code, I would say Claude will be 1st, and on the 2nd both Argon4 and ChatGPT.
However, If i'll make a tier list regarding the overall experience in long term, I would say Antigravity Pro subscription its not something I would recommend.
The first will be Claude, the second being Codex. If it was something besides Antigravity, I would put that on the 3rd place.
The overall tokens pool you have its so so small. I've made some comparisons, and Indeed are so small. The Claude opus 5.5 Medium model on Antigravity consumed its 5hourly limit and 49% of weekly limit from 1 prompt. For Argon4 I was able to work with it for at least 1 hour before consuming the weekly limit. And Flash 3.8... its.. idk, i just simply dont like it, it is not feeling capable of the task I usually running.
On Claude desktop, opus 5.5 I usually work for like 4-5 hours straight. Rarely hitting the 5hour limit. Same with Codex Sol 6.1
I just brought the Pro plan from Gemini being hyped about Argon4 and being curious how is it. Overall the model is capable of many things, but the overall Antigravity experience its not. Like for ~20euros Pro plan subscription to have such a small pool to work with comparative with the other alternatives, I would say, claude or Codex will be a better choice. I'll not renew the plan on Google.