KC Green's webcomics are some of my favorites. He is mostly known for Gunshow, which ended a while ago, and he's currently doing one called Funny Online Animals. I highly recommend it, as well as some of his other works, including He Is A Good Boy and his adaptation of Pinocchio.
I like Achewood as well, though it is a very long read. TGWeaver's comics are classic too. RubyQuest is probably the most well-known of them, having led to the creation of /qst/, but I'm partial to DiveQuest (unfortunately it's been a long time since that one updated).
And if you like shidposting, read Super Mega Comics. It's quite unique and displays a pretty sophisticated sense of humor at times.