To be perfectly honest, I'm usually the one stuck being the Healer/Leader/Whatever. Not that I mind it, I've always played Healer classes, Night Elf Disc. Priest in WoW, Half Elf Bard for DnD's, some good fun in that, sometimes even an artificer.
However when I'm left to play by myself, say... I'm playing Dragon Age, I'll usually pick up a Tank of a Warrior or a lethal to everyone Mage. Always a Human or Elf in Dragon Age. Never picked a Dwarf, in anything for whatever reason. Just something always put me off about them. I've liked having Dwarves around, Ohgren for example, but I could never get my head around playing one myself.
On another note, out of everything I've played... Never touched a rouge class. Why? I suck at stealth. I know from experience from trying to use stealth effectively with other characters,or even small stealth sequences in games. I'm horrible at them. And the only other choice for being a Rogue is to be an archer I suppose, which actually isn't all that bad.
Actually, HUURRRDURR, I played an Archer Rogue in DA2, so I suppose I have. But never touched the stealth tree in that, I was an acrobatic bugger that did backflips and shot you in the face. Ah, it was quite fun.