I was thinking about this and if the intent is to have a second toon just to boost an alt to 60 and then discard, you'd probably want a pure ranged dps. A BM hunter or demo lock would give you a pet to help with the elite quests and the click macros for dps are pretty simple to setup.

I was thinking of this solution as the machine gun following around your alt. A mage would be nice too. Personally I'd avoid the elemental shaman because they tend to come into their own late in the game, but locks and warlocks are killing machines right around level 10.

I did RAF on 10 accounts and have about 70 toons over level 60. The lock teams and hunter teams just flew through the old world. I'd lean towards a hunter since they keep killing even oom.