For a multiboxer, especially with a elemental shaman group, the paladin is the tank to pick.
- Lowest actions per minute (compared to mildly higher for druid and very high button mashing for warriors)
- AoE tanking
- Synergy. Pally threat is done with spells, Wrath of Air is a significant boost for the pally, but useless to the druid and warrior for example.

Forget about this or that tank class taking more damage. While there are difference between the different classes tank talents and mechanics, it is balanced. Paladin tanks for example are not just for trash. I tank bosses in MH and BT as I please on my paladin tank. Paladin tanks have been the boss tank on world firsts in BC raids. Looking at just one number and proclaiming you have the answer is shortsighted. Take 10% vs 6% & argent defender ability for warrior and paladin respecitvely. With overhealing and another blow killing you, the difference is in actual fights basically none.