Quote Originally Posted by Inuk9 View Post
Blm. Thunder IV, flares and foul if the battle takes that long...
Not to mention you can Triplecast three instant flares for nearly 800 potency AoE in 3 globals.
I would be really surprised if the answer to the OP's question isn't Blm.

Maybe the melee classes have better sustained AoE over a longer period, but I have trouble thinking of any examples where you actually need sustained AoE...