Retribution paladin is a really good support melee in this expansion, until ToC and ICC content serves mostly as a must-have support but not as a real damage dealer on the high-end. On the contrary, since ToC and ICC with the great set bonuses, trinkets and of course the legendary axe, Shadowmourne ret paladins are top3 after mages and warriors...
Protection paladin is one of the best if not the best tank class in this expansion. It has a lot of raid utilities, great threat generation and amazing survival abilities both cooldowns and maintainable survival spells like Holy Shield. Protection paladin is a must-have for both 10man and 25man raids during all the expansio
Holy paladin is one of the best healing classes in this expansion and the best tank healing class without any doubt. It can never run out of mana with correct itemization and can always cast non-stop. Holy paladins have many utilities and a really useful class to bring it to all the raids.