What is better for a group in World of Warcraft?

It won't be for a while but, when cataclysm comes out my friends and I are going to make a group. there will be a Warrior tank, a Warrior DPS, Rogue DPS, Priest healer, and myself. I would like to know what is better for this group, me being a feral druid for DPS (also for back-up heal and back-up tank) or should i be a Mage for ranged DPS (also water/food and ports) they both have their pros and cons. I just want to know what you all prefer.