I like Adventure Time. It seems really weird if you just watch an episode or two, (and yes, it still is pretty weird to begin with), but there is this really, really deep backstory about why the show is as weird as it is, and they've mentioned it multiple times on the show.
I think the best shows on CN right now are Regular Show, Adventure Time, and Incredible Crew is working its way up there. Believe it or not, it's actually a pretty funny show, despite the fact that it is live-action.