2v2 partner preference?

Hey all. I recently got one of my buddies into the game and he wants to try some arena on his rogue. I have a druid and a paladin. If we're looking to have some fun and push a little rating (maybe 1800?) would it be better for me to be feral, resto, or ret? How about unholy dk? He's learning the class as mut right now but he's open to changing to sub once he gets a little better but he'd probably rather stay mut if that affects the decision.
Thank you all for any suggestions!