King Dedede
Surprised that not many other people seem to use him much, I just think he's so awesome. For one he just looks cool, a giant penguin in royal garments with a huge sledgehammer? I'm digging that. On top of that he can throw Waddles Dees everywhere and definitely has the best Final Smash in the game. He's heavy so he can't be thrown far and boy does he pack a punch, wouldn't have it any other way.
On the other end of the spectrum though I play as Captain Olimar as well, not as much as Dedede, but he'll always be my second choice. He's fun to play as and I choose him more because of how much I like Pikmin and how cool he is rather than how good of a fighter he can be. Those Pikmin make the best noise when they're thrown.
King Dedede, Living Legend.