Headlines is the only good Leno bit, in part because almost anyone could do it. All he had to do is hold newspaper clippings (compiled by someone else) up to the camera and read them out loud.
Funniest thing I saw Leno do was be a guest on Letterman back in the 80s when Leno was just a stand up comedian, he told some funny butt and fart jokes.
Jimmy Kimmel was pretty much my only reason for watching that show back in the day. He was more fun to watch when he was making fun of the creationist dinosaur on a nightly basis.
You're in a lot of trouble as a comedian if Jimmy Kimmel, the second least funny person to be named Jimmy and have his own show, lectures you on comedy.