Destil
Explorer
I'd hate to think we're living in a world where CharOp's opinions matter, though...FWIW, CharOp generally considers Paladins to be the most powerful defender in the game at the moment, due largely to their ability to punish multiple enemies via Divine Challenge/Sanction in a turn -- while Fighters and company may be sticky, their marks still require Immediate actions, which means you can only tag one of your marks per round.
Compared to a fighter all other defenders look a bit weak. Having played a paladin from 5th-16th level I'm fairly happy to say I find the class excellent. Their leaderish options (especially save granting) are great and they can fill in for healing in really tough fights. Or as a friend says, lay on hands is retroactive defending. "Oh, sorry about that monster that got by and hit you, let me spend a surge to heal you." They're easily the second best defender at range (after a swordmage), and most of the build options are interesting and have some good value and worthwhile focus.