Marth, although he was a damn-sight better in SSBM. He was perfect for juggling opponents and for keeping enemies just at the tip of the blade where it did massive damage.
Wolf. Weird choice, I know, but he's a fast tank. Took me a while to get used to him, I'll admit, but once I did it basically became a match of people going on the defensive; then I'd just pound them to bits.
Lucario was also someone I played as for a while, until I discovered wolf. He was mostly a rebound after I got bored as Marth. It was his grace that got to me, the way he seemed to move so slowly and controlled, whenever I play him it just seems easier to get the timing right. His Final Smash is arse, but he's not a bad player.
Oddly, I find that whatever character I play as pretty much uses the "A" attacks and little else, 'sept the odd grab for too defensive opponents, or a counter/reflector shield when caught in a tight spot.