If I could add one, though, it would be Craig Ferguson. He's a smartly self-deprecating and often delightfully goofy host. The times I've tuned in, he has traded in gentle but pointed give and take with his guests which has been entertaining enough, but for my money the reason to watch is for what he does when no one else is on stage with him. He trades in absurdity and pulls off silly routines with props that would fall flat in anyone else's hands. (He, rather than Stewart, should be the one doing the absurd "Gitmo" hand puppet bit, for instance, even though the political content is squarely within Stewart's milieu.)
The reason Ferguson came to mind is that he was unexpectedly put into a tough spot last Friday. As he explains in the video embedded in this Hollywood Reporter article, he had to ditch a segment of his (prerecorded) Friday night show because it made reference to the new Batman movie, a subject that was obviously taboo in light of the mass murders in Aurora, Colorado. Though his impromptu explanation of the incident was unwontedly solemn, his natural charm still peeked through.