SmackJeeves gets a lot of love on here, so you're probably best off sticking with what you know. I recently signed up for a mirror site with them and switched to a paid subscription because I like their stats tracking and CMS. I'm getting decent audience growth and a couple of active commentors there as well. (Incidentally, if anyone knows how to set up PW tower ads so they run alongside the comic and/or comments box, please tell me)
Neko the Kitty used to be on Comicgenesis back when it was Keenspace, and I thought their customisation options and help pages were really good, and at the time they were more generous with their file storage than SmackJeeves are. Can't speak for them now though.
We haven't seen Gibson in a while, and I kinda miss the guy, so I'm going to bring up DrunkDuck in the hopes he'll come in and tell you why you shouldn't sign up for DrunkDuck.