I went with a Disc Priest, but can see a strong argument for any healer type.
With this composition, you cannot really go that wrong.



Druid:
- Hots, Thorns, Battle Rez, Cyclone, Instant root, Tree of Life, initial Stealth until you need healing.

Paladin:
- Hammer, Bubble, Resistance Aura, Beacon, Word of Glory, Hand of Sacrifice.

Disc Priest:
- Pain Suppression, PW: Shield, Fear, Mass Dispel, Power Infusion, Drain Mana, PW: Barrier, Smite healing.

Holy Priest:
- AoE heals, Chakra, Spirit of Redemption.

Shaman:
- Tremor/Grounding totems, Healing Stream with resists, Reincarnation, Earth Shield, Heroism/Bloodlust.