Survivability wise, hands down my 4 hunter druid team. I had used 3 gorillas and 1 wolf for my team before 3.1. For fun my 4 locks + priest team. For outlands both teams just destroyed everything. Once I got to northrend though it's a different story. instance mobs and bosses just hit for much harder. You can do the normal instances but doing heroics is out of the question.

One thing with the lock team while questing. It took a little getting used to at first. You have to use a spell that deals direct damage first. Many times I would dot up a target and my 4 felguards would kill them before the dots did any tick damage.. so I would not get credit for it. Immolate is great but 4x immolate from my locks would almost kill anything anyways. You gotta find areas where mobs are packed nicely then you can just dot once and run.. let your felguards pick up the pieces.. and they do an awesome job of that.