Based on my group's battlerager fighter, I would say it's probably the toughest of the bunch. Lower defenses, sure, but hot damn can that dwarf crank out the damage. With a mordenkrad he can do roughly 25 damage with his melee basic attack, making it nearly never worth it to provoke the OA to go after the softer targets. Not only that, but he does have 18 healing surges, which means I have a very hard time putting his life in danger.
If you're still looking at multiclassing as a leader, the battlerager in my group is paragon multiclassed cleric, giving him access to powers that are close and area burst attacks, meaning he can mark nearly anyone he wants, any time. That, and he can heal the group in a pinch, and give himself regeneration, which, when coupled with the temp HP he always has, means he can ignore about 15 damage per round.