Paladins aren't overpowered.
Shamans aren't overpowered.
Rogues aren't overpowered.
Hunters aren't overpowered.
They are balanced, and have different purposes. If you can't kill one of them, change strategy, there is always a way. They are probably the most balanced classes I have ever seen in an MMORPG, much better than what FunCom did even 3 years later.
Warriors need to be tweaked. They seriously need some loving, a warrior cannot kill another class played by an equally competent person, with the same equipment/level etc... A very good warrior with the best armor will win against a newbie paladin wearing cloth rags... and even then the fight would be a close one

Once again, if you think Paladins are invincible because you can't kill them, you are probably not doing it right. I am sick of reading 'nerf posts', only warriors are allowed to complain.