Conan vs Fallon and other talk shows

As an european watching Conan, Letterman, Fallon, Leno, Kimmel, Colbert, etc, for years, there is something that I still don't understand when I go around the internet forums.

The hosts/shows with better ratings are usually the mainstream, easy comedy, boring ones like Fallon who basically puts a variety show. Conan on contrary pushes the envelop in comedy, he doesn't get it all the time but when he does is absolutely brilliant. I really don't understand how people in America are into lip sync and stuff like that like celebrity games, but whatever grinds your gears. Even in terms of interview that I keep hearing Conan is not very good, he is still way better than Fallon who just keeps laughing throughout the interview.

For me, Conan is on the top, like it was Letterman and Craig Ferguson. From nowadays hosts I see a lot of potential on Jimmy Kimmel but he needs to stop caring for the "mainstream" America and start pushing the envelope.

These are my 2 cents as an european following the american talk shows for a while.