As a very young kid, I liked Millie the Helper, because Rita Moreno simply screaming "Hey, you guys!" was enough to entertain me.
As I got a little older, I tended to gravitate to all the Morgan Freeman characters: Easy Reader, DJ Mel Mounds, and Vincent the Vegetable Vampire. I also was partial to the animated Mel Brooks character that read words on the screen (don't know if the character had a name).