My vote for "best" PvE team is:
- Prot Paladin, Warlock, 3x Elemental Shaman.

For PvP, probably go with:
- Frost/Blood DK, 4x Ret. Paladin.

For both, maybe something like:
- Dual Spec Druid (Feral Bear - PvE & Boomkin PvP), 4x Elem. Shaman.



There aren't right or wrong combos.
If you're having fun, that is what counts.

At the moment, I'm playing:

- 5x Feral Druid
- 1x Prot Paladin, 1x Demo Warlock, 3x Elem. Shaman
- 1x Disc Priest, 4x Affliction Warlock
- 5x Priest
- 5x Hunter
- 5x Death Knight

The Ferals are getting most of my time, but the others all log in, too.