I've been watching Conan for years, way before Andy left, in fact the guy got me into talk shows. So theres no question who the best is.
Leno I'll watch but mainly only because he comes on before Conan. Headlines is about all the guy has.
I hate Letterman. The guy just isn't funny.
Stewart is the man, second only to Conan.
Carson...all I can say is that I'm actually impressed he still has the show. As far as interviews go he's not that bad. He just doesn't offer anything else to the show. He doesn't have a personality. Anyone else could replace him and you'd never notice. Doesn't bring a single thing to the show.
