There are two compositions which have proven strong, boxed.

Four shammies, because of the totem farm.
This is usually accompanied by a healer, played by someone else.
We get fear immunity, a lot of buffs and resistances, heroism/bloodlust, purge, and controlled burst.

4x Ret's, with the DK is a more resilient team, higher armor and such.
Plus they are in your face immediately.
The loss of cleanse will make fear a nastier mechanic to face.

A mixed melee team... something like:
- Death Knight
- Enhancement Shaman
- Warrior
- Ret Paladin
- Ret Paladin or Feral Druid or Dedicated Healer?

You gain Tremor for the vs Fear.
And several buffs.

But lose the passive heals of Divine Storm as well as Art of War heals.
Not sure if the other teams have enough healing to be in the same ball park as the DK/Ret's.