If you are queuing solo mostly sorc is the way to go since you can have multiple roles if you choose to. That being said, do you really want to play a class that 75% of the other players play aswell?
Marauder does quite well without healer btw, you go in kill 1 guy, use that stealth thing to sneak away, heal up and go back in. Or use that ability that reduces dmg taken by 99% and do the same.
Personally I wouldn't play either. The real question is not what's better in pvp, it's what you like to play best... and go from there.