Now that’s a rare take. Usually the first 2 seasons are regarded as the worst and have very childish humour compared to later ones.
Season 10 is pretty much the start of peak South Park. It had the Cartoon Wars two parter and the iconic Warcraft episode. Also introduced ManBearPig and the “Nice” meme …
I think my least favourite season would be the 20th which is the whole Garrison as Trump story line. They really wrote themselves into a couple of corners with that one. Though the troll-trace subplot is amazing.