if you didn't want to quest i'd prob say go with the lock - I have seen some voidwalker / seeds of corruption aoe'ing that though isn't on par with what a pally or mage can do would still be faster than killing mobs one at a time with a rogue well imo.

though... since you can play three at the same time, i'd say lvl up three toons together put another caster on follow and control the war on your main client.. it will prob be just as fast for you in the end and you will get more free gift lvl's to grant to any alts you have on the main accounts.