Re: Jimmy Fallon to take over for Conan O'Brien
None of these guys can top Johnny Carson. But while Carson wasn't a great stand-up comedian or writer, his show was the best. I believe it's because he was great at the most basic element of the show: the interview. Of all the people mentioned in this thread, Letterman is the most like Carson when it comes to the interview. Carson had some funny bits (that would be too tame by today's standards) but most of the time it was his reaction in the bits that made them better.
Honestly, rarely watch any of the late-night shows anymore. Leno is a terrible interviewer. Conan's show always seemed like he was a college kid doing a public access show. Letterman seemed like he stopped caring.