Maybe I'm in the minority, but I don't find very poor parenting to be funny.
Runners-up: Blondie, Single and Looking, Family Circus
Runners-up: Zits (I liked the blort! sound effect), Doonesbury (Zonker's line "many of them profitable" is great),Candorville, Garfield, Lio, Opus, Pearls Before Swine, Agnes, Brewster Rockit: Space Guy! (this is really a one joke strip (Brewster is stupid), but it's a joke that still amuses me for some reason)