imo, if you are a good player who likes a challenge, then go prot.
Alot of people will say it's easy, because it is, but then imo every class / spec is easy.
Tanking in general, is imo the most rewarding of all roles within a raid, and you feel a true part of the raid and crucial to it's success.
Holy you get soo caught up in lifebars that you don't actually get to see much of the content.
Ret is soo lacking in responsibility that you'll bore yourself to death, it's heaps of fun on farm content since you can compete on dps meters, but progression you have very limited impact on the success or failure of the raid, and thus you feel insignificant (because you are insignificant)
Prot however, you have huge responsibility, if you screw up the raid screws up. If you are good, you can not only control your performance but that of the raid aswell, since you are the one who is in control.
For myself, I enjoy being in control and having an impact on the raid's performance. The amount of times, while on my alts, I have raged to myself about how we'd never be wiping if I was on my pally.
Also besides that, prot as a pally is fun, you are a god of soloing, you can solo what other tanks can't even solo! It might not be quick, but you'll do it. If you goto a battleground in your pve gear, you won't just instantly fall over dead, you'll survive and smash face while you do it.