Probably Restoration. BiS Resto stacking resil can get to absurd amounts of effective health. Riptide is an instant cast as is ES so you have two guaranteed self heals that can't be interrupted outside of blankets. Only issue is keeping your buddy up.
Elemental hits like a wet noodle. I don't like it, I feel like it's been pretty gimp since Wrath...at least that's the last time I remember enjoying elemental.
Enhancement *should* be decent. This is roughly what I would go with, 2nd profession is optional.
chardev 10 - Mist of Pandaria - BETA
Note that the PvP Power stat is bugged in Chardev, and the character actually has 16.3%.
Against targets with no additional resil and around 40k HP, that build should be able to one shot them with Lava Lash assuming a full stack of Searing Flames (assuming that is even in the game anymore lol).
As far as Arena goes, yes it is bursty. I can two shot a 80 Resto Shaman with 60k HP 75% resil as Arcane blowing all my CDs. Anyone can die fast in the right scenario.