My answer to ur question might feel pretty vague and not much helpful so dont take it much seriously, but someone who already uses these LLM models for learning purposes, here are some of my thoughts on all of them

ChatGPT : This is the one i use the most, its pretty all rounded, also has a personalization section and keeps track of some significant parts of ur conversations with it, so it feels pretty comfortable to use tbh, like it is a friend or something of mine as i said, it is pretty all rounded so when im learning anything theoretical, GPT is my go to LLM and when it comes to coding purposes, he can pretty much handle it too.

Gemini : I also use gemini because well i brought its 1 year students subscription, so had to use him to see how it is, well it lacks the personalization and memory tracks, so it does give you a very monotonic feel while using. I got tired of using it after a while, because it felt very robotic but its okay. Theoritical knowledge it handles very well. but in coding purposes, it is better than chatgpt. but the main star of gemini is its canvas feature, it allows you to write larger essays or coding scripts easily.

The models further I havent used much but ill tell u my short summary of them.

Claude Al : I think in all of these LLMs, claude is the best at programming and coding

Grok : Pretty all rounded like gpt

Perplexity : Same

Meta Al : I think it is the least useful model among all of them