I love the Elgin Theatre. It's classy, without feeling pretentious.
I think it's the hanging vines and leaves which give it a more homely, organic vibe.
The best comedy show that I ever saw was Louis CK at the Elgin a few years ago. He had just separated from his wife, so his comedy was as raw as I've seen it. We were dying for the full 90 minutes, and I would have been rolling on the floor if the seats weren't so comfortable.
I've also viewed a bunch of TIFF films and some other dramatic performances here. Consistent warm feeling and atmosphere every time.
My pick for top theatre in the city.