It’s impossible to pick from 10 seasons, but I keep going back to Chandler and Monica’s proposal as Matthew Perry’s finest moment on Friends because of how deeply felt his performance is. Yes, Perry was a sarcasm god, but his sincerity and sensitivity shines brightly here.
something i don’t think a lot of people know - matthew perry came up with TONS of the jokes on friends. the writers would literally go up to him and ask for input if they got stuck on lines because they knew he had such good comedic instinct. he deserves so much credit for that