Bill Clinton is a flawed man, which puts him in good company. Is he really worth all the bile that is spewed at him from the right?
Runners-up: Beetle Bailey, Close to Home, Dennis the Menace, Family Circus, Speed Bump
Most strips have one joke, usually bad, that they lead up to in the first two or three panels. Darby Conley today has a joke in each panel, and they're all funny. The fact that his jokes are often good puts him in the top tier of cartoonists. The fact that he often gives two or three or even more jokes for the price of one makes him, arguably, the best (Mark Tatulli would be the other candidate who would deserve a long look).
Runners-up: Agnes, Big Nate, Doonesbury, Pearls Before Swine