Well, as Jelly said, it's pretty hard to NOT play at least an average Marth, the guy is extremely user-friendly. Granted I think that was more true in Melee than in Brawl; Falchion's reach appears shorter. Back in Melee Marth was my "big guns" despite Yoshi and Mewtwo getting far more play time. Although the fact that the AI was dumb as a doorknob back then helped a lot too.
EDITS MUCH LATER: Playing random matches online now, I'll be on 'till midnight at least. I see Akamaru online but he's not hosting, so I can't join.