The rise of Snoopy is, in my opinion, one of the faults of the later Peanuts. The early strips generate their power from pathos. As the strip becomes more unrealistic, it loses a lot of this power. Therefore, I am firmly not a member of the cult of Snoopy. I still think Peanuts is one of the greatest strips of all time though.
Runners-up: Dennis the Menace, For Better or For Worse, Garfield, Mother Goose and Grimm, Speed Bump
Tony Cochran has a great ear for comedic dialogue.
Runners-up: Frazz, Get Fuzzy, Piranha Club, Sherman's Lagoon