I sometimes watch when I get home from work after second shift, and I'm pretty much a night owl. Seth is my favorite by far. I do enjoy some of the games and things that Jimmy Fallon does, plus we got to go to his studio when we took the NBC tour back in July so I watched it a bit more after that, lol.
I actually rarely watch Stephen Colbert, even though I like him as a comedian. I agree with his politics but sometimes the monologue is a bit much. And I know it's a stupid reason, but the woman that does the announcing for him has a super annoying voice to me so I don't watch much because of that. If there's a guest on I want to see I'll watch.
Generally I don't like Kimmel at all, he comes across as smarmy to me. I'll probably watch his show some next week in solidarity (I'm on the early shift this week so I'm not staying up, plus I don't have a DVR any more to record it).