For the longest time, Paladins were the only very strong AoE tank.
With the release of WotLK, Warriors, Deathknights and Druids can all effectively AoE tank, like the Paladin.

At lower levels, a Balance Druid in Moonkin form, using mostly Huricane can probably boost the quickest (of the druid specs).
Eventually, the survivability of a Feral Bear, with Frenzied Regeneration and Swipe spams will allow for larger pulls and surviving through them.




You have two accounts now, and are thinking of boosting four accounts with your druid (total of five accounts)... or boosting three accounts with the druid's account (total of four accounts)?

Call the druids account A.
Your existing other account is B.
Your new accounts are C and D -- or -- C, D and E.

Account A cannot be linked to C, D or E, if it will be used to boost.
If B is linked to C, D and E, then B must be on and grouped with C, D or E for any RAF bonus to occur.
Levels gained on C, D and E will result in levels granted on B.
For every even number of toons that reach 60 or higher between the boosted accounts, B gets a level 2.99 toon boosted to 60.99.

I'd personally go with something like... (Four total accounts)
A is boosting account.
B refers C.
C refers D.
Levels gained on D equals granted levels on C. Levels gained on C equals granted levels on B.

Or...

A is boosting account. (Five accounts total)
B refers C.
D refers E.
Levels gained on C equals granted levels on B; levels gained on E equals granted levels on D.

It all depends on which accounts you want the granted levels, and to a lesser degree which accounts get the Zhevra Mount (which saves you about 100g if its a new to 60 toon).