The sentiment in this thread surprises me a great deal. For me, Gemini 2.5 Pro is markedly worse than GPT-5 Thinking along every axis of hallucinations, rigidity in its self-assured correctness and sycophancy. Claude Opus used to be marginally better but now Claude Sonnet 4.5 is far better, although not quite on par with GPT-5 Thinking.
I frequently ask the same question side-by-side to all 3 and the only situation in which I sometimes prefer Gemini 2.5 Pro is when making lifestyle choices, like explaining item descriptions on Doordash that aren't in English.
edit: It's more of a system prompt issue but I despise the verbosity of Gemini 2.5 Pro's responses.
I've found Gemini to be much better at completing tasks and following instructions. For example, let's say I want to extract all the questions from a word document and output them as a CSV.
If I ask ChatGPT to do this, it will do one of two things:
1) Extract the first ~10-20 questions perfectly, and then either just give up, or else hallucinate a bunch of stuff.
2) Write code that tries to use regex to extract the questions, which then fails because the questions are too free-form to be reliably matched by a regex.
If I ask Gemini to do the same thing, it will just do it and output a perfectly formed and most importantly complete CSV.
For writing code at least this has been exactly my experience. GPT5 is the best but slow. Sonnet 4.5 is a few notches below but significantly faster and good enough for a lot of things. I have yet to get a single useful result from Gemini.
I frequently ask the same question side-by-side to all 3 and the only situation in which I sometimes prefer Gemini 2.5 Pro is when making lifestyle choices, like explaining item descriptions on Doordash that aren't in English.
edit: It's more of a system prompt issue but I despise the verbosity of Gemini 2.5 Pro's responses.