It's up to me, but Kirito alone represents sao's problems since he's its official face. I followed the anime from seasons 1 to 4 when they came out, and while it's certainly better in the LN, I find it pretty lame as time goes on. Arc 1 is cool, but after that it varies a lot, leading up (in my case) to the end of alicization with pitiful scriptwriting ease.
And I come back to my opening sentence, Kirito, it's the same thing. He's sympathetic at first, then more or less a pain in the ass as time goes by and, above all, he's a fucking gary-sue by the end of season 4. So, like a lot of shonen heroes, he's a pain in the ass for me. Combine that with the fact that he has a potential harem (purely theoretical considering he's loyal) including some of the most high-profile waifus (hello suguha fans) and you've got a character who's sometimes arrogant, strong at times for nothing and, what's more, incredibly lucky (sorry, but the pyjama party in season 4 is lunar).
So there you go, once again, that's just me. However, as an NTR fan, seeing Asuna get corrupted is a pleasure, but seeing Kirito finally lose something for real without the scenar helping him is a bonus that makes me happy.
PS: English isn't my native language so I'm going by deepl. Sorry if some idiomatic expressions don't work.