I love the contemplativeness of Copper [http://www.boltcity.com/copper/], and for pure weirdness I can't get enough of A Lesson is Learned [http://www.alessonislearned.com/], though both of these I think are on a kind of permanent hiatus at the moment. Same thing with Perry Bible Fellowship [http://pbfcomics.com/]. So, I guess the one that is my favorite that still posts new comics would have to be Achewood [http://www.achewood.com]. Of course, I won't get in to some of the annoying stuff he's been doing lately, but a lot of the comics are still good.
And of course Toothpaste for Dinner [http://www.toothpastefordinner.com].