Cat - Great single target dps.
Pally - Great multi target tank.

Healing druid - many different healing spells to choose from, including Hots, AoE, and great way emergency mana recovery. IN-combat REZ!!!! hard to take down in bear form if pally dies.
Healing pally - several healing spells. hard to take down if cat dies. Bubble+Hearth in case of emergencies. Out-of-combat rez.

personally, i'd go with pally tank druid healer. but you just have to try both to see how it fits your style.