What's the current best Mac to buy for offline LLM in used market?

I am seeing 96Gb Mac studio 3rd gen I think for a good amount but I guess it would be better than paying for mac mini newer models with lesser ram?

Or would it make sense to buy used 32 GB Mac mini 3 or 5?

Is there a cost/dollar for various generations which I could compare against used market and pick the most effective one?

Why does it have to be a Mac? Your money probably goes further with a generic PC and Linux?