I have a lifelong love of my Prot Warrior, the rotation can be a bit button mashy but Blood & Thunder/Shockwave was just so awesome (RIP BnT), and of course who doesn't love charge and heroic leap?
But I've found the new Prot Paladin much more enjoyable than it used to be. Only real downside is that when you tank on a Paladin it sounds like you're ringing a bell the whole time :P
I haven't played paladin nearly as much but I find warrior tanking a bit more entertaining (mostly due to the added mobility frankly:P), my favourite is definitely DK though (death strike is such a nice mechanic).
I like my prot warrior, but with the new active mitigation rage generation feels really clunky to me. Feels like I am constantly waiting on rage to use any mitigation which has taken all the fun out of it for me. After 6 years of Maintanking on him I have switched to a dps toon.