I don't know about Adventure Time. I've tried to watch it but it really doesn't catch my interest. Then again, Cartoon Network doesn't really make shows worth mentioning anymore.
I remember watching things like Johnny Bravo, Ed, Edd, and Eddy, The Powerpuff Girls and Dexter's Lab.
Those were the shows I grew up with and I don't feel that Adventure Time is on the same level as those shows.
I wish they would have given Marshall Lee a voice and some more of a stand out part in that episode.
Maybe they'll bring him into the series again somehow.
My alltime favorite characters would have to be Princess Bubblegum when she was 13, and BMO.