Why does Conan keep getting credit as a major influence on the Simpsons? He was responsible for what, three episodes over two years? Because he's the only writer whose face people recognize, his importance gets way inflated.
I haven't watched Letterman for a couple years now, really, but I always dug him when I watched. His style of comedy is a very personal one, if that makes any sense. I liked that particularly vapid celebrities feared going on his show, the unscripted interviews, and the thinly-veiled contempt that would come out now and again.
Hey, remember Andy Richter? Good times.