I have sent the same prompt to GPT-5.2 Thinking and Gemini 3.0 Pro many times because I subscribe to both.

GPT-5.2 Thinking (with extended thinking selected) is significantly better in my testing on software problems with 40k context.

I attribute this to thinking time, with GPT-5.2 Thinking I can coax 5 minutes+ of thinking time but with Gemini 3.0 Pro it only gives me about 30 seconds.

The main problem with the Plus sub in ChatGPT is you can't send more than 46k tokens in a single prompt, and attaching files doesn't help either because the VM blocks the model from accessing the attachments if there's ~46k tokens already in the context.