I'll recommend:
Druid Tank, 3x Rogue DPS, Resto Shaman as the healer.

You get a lot of totem buffs, and bloodlust/heroism from the shaman.
Who also brings Chain Heal, Riptide, Earth Shield, Lesser/Healing Wave etc.

A druid is a strong tank, and it is different from the pallies you have on your first team.
I like pallies more then druids for tanks, but you already have four pallies and the druid is a good choice.

If you don't have either an Elemental (caster teams) or Enhancement (melee teams) shammy on the team, a Resto Shaman is a very strong option.