No question it has to be Homer haha. We see Homer as not only a funny, clumsy man, but also a sweetheart when it comes to his family, case in point, the season premiere (Stark Raving Dad), where he had to spend time in an asylum, where he then crafts a song with his room-mate for Lisa :)

In "When Flanders Failed" we also see that even though he wished Flanders failed in his business, he and his family end up shopping and thus, saving The Leftorium.

Besides these sweet moments we also get to see him be a country music manager with Lurleen, meet his half-brother Herb in the finale and mending their differences. We also see him stop a meltdown with a "lucky push" and finally we also get to see him do what he does best and that is being AWESOME!! in "Homer At The Bat" where he wins the game for his team with, a you guessed it! haha a HOMER!!! :D

Sorry if my comments are too long, I really adore the show and the first few seasons are like burned permanently into my memory hahah :D

it has to be bart