Obviously, Luigi is my #1 choice, but simply because I've done much better with him in both Melee and Brawl than with anybody else, and I've used a number of characters besides him including Link, Ike, Lucario, Marth, Mario, and possibly others that I'm not thinking of at the moment. Though Mario is a bit similar to Luigi in Brawl and was even more similar in Melee, I never did nearly as well with him.
I could probably get good with other characters besides Luigi, but not to the same extent. Luigi, I got the hang of him fast. Everybody else was another story.
