-Cyanide and Happiness is definitely my favorite webcomic. It's so silly, simple, and twisted... and that's exactly what makes the whole thing work. Fuckin' classic.
-Perry Bible Fellowship is good fun as well for similar reasons as C&H, except cranking up the twistedness to 11. It's a shame the dude had to pull that bullshit of charging for strips we previously saw for free.
-Buttersafe is generally just plain ol' goofiness, but it's damn fun at that.
-I kinda like to read Brawl in the Family sometimes, though some are hit-and-miss with me; for the most part, however, I enjoy it, being a massive Nintentard.
-Gunshow Comics. That is all.
-I used to read Slightly Damned, but I stopped seriously following it last year, because holy shit, does it start to go nowhere from there (the story as a whole was pretty slow up to this point, but now it's just unbearable). I sometimes duck in to check up on it, but it's still insanely slow, even with updates twice a week now (especially due to many updates consisting of one-panel splashes that don't contribute to the story, but aren't asides either).
-I've recently started reading Culture Shock, and I think it's pretty good; it seems that the author knows how to pace his story just right (at least better than Slightly Damned). It also does the whole clashing cultures and time periods aspect cleverly, with a great mix of comedy and drama.
-I dunno if it counts, but The Oatmeal's stuff is always just amazing.