You could not pick more different classes even if you tried. ;P
Prot Pally: The best multi-mob tanks. They are great at taking on many mobs at once, but lack a bit in bigger 1 on 1 fights, like bosses. Not saying they can't do it, on the contrary, but they do not excel at it.
Feral Tank Druid: The best damage mitigation and health pool. Also, excellent single-target threat. (Better than Warriors from what I hear) They will not have as much avoidance as a Warr or as many "Oh sh-!" buttons, but they can take a hit like none others.
Basically, they excel where the other one lacks a bit. That being said, a Feral Druid will still be better at multi-mob tanking than a Warr as far as I know. I tried tanking with both, and I prefer the Druid's way, but I know some people feel the exact opposite.
Now, healers.
Holy Pally: Hands down the best single-target healer. Can easily top the healing meters as long as he does not have to multi-target heal too much. Plate protection is pretty good in PvP but not so much of a difference in PvE. Higher survivability through abilities like bubbles and the like.
Resto Druid: Superb healer but I do not have much hands-on experience with one. I played my Druid as a healer before the expansion so I do not fully know the beauty of the new HoT's. Although I do know you can maintain a stack of 3 Lifeblooms on someone while throwing HoT's around and help topping everyone. You will probably not top the meters as much, but you'll be helping a lot. AoE heal (Tranquility) can be pretty useful too. Not a lot of "Oh sh-!" abilities for PvE but in PvP shifting in and out of Travel form will make you a pain in the *** to kill. Spells cannot be interrupted if you rely on HoT's only.
I swear, if I dive back into WoW sometime, I'm finishing leveling my third Druid and I'll play with both Feral and Resto. Such a beautiful class...
So yah, I'm biased a bit because of my love for Druids, but I played a Pally and have gone Holy for end-game, although I do know about Prot a bit since I'm a regular at the Pally forums as well.
Hope this helps a bit. It's highly based on playstyle preference, etc, though.