IMHO, Donald O’Connor steals the show.
Absolutely O’Conner stole the show! Stanley Donen directed probably hundreds of films from the 1940’s on and not just musicals. He directed Charade with Carey Grant and Audrey Hepburn. I didn’t care much for musicals until I watched On The Town with Sinatra, Kelly, and Ann Miller.
I interviewed Donald O’Connor for my radio show back in 1992, super nice guy, He related this story about “Make Em Laugh,” He was off set for 3 days after shooting the sequence, when he came back there was much applause and praise for his performance. Then Gene Kelly took him aside, and asked him, “you think you can do it again?” The footage was destroyed for the first take! https://www.google.com/amp/s/www.thevintagenews.com/2017/12/13/singin-in-the-rain-trivia/amp/