4 mages and a priest is a very fast and powerful AOE group. My first 5x man team was this and for the first 68 levels, I just walked through everything. It wasn't until I got to the Nagrand quest, Durn the Hungerer that it became clear that this group would had some major pitfalls. (no tank). I built them deep into the arcane tree but enough fire to get an instant cast pyroblast. There really wasnt ever a need to use frost nova, flamestrike, blastwave or blizzard. Arcane Explosion with holy nova/circle of healing was more than enough to get the job done.

Their HP is their armor so PVP style gear with lots of Int, Sta, and spell power worked out perfect for this group. I didnt care about any other stats really and free water kept downtime to a minimum.

This group would still be an absolute epic trash mats farming group.

If your looking for an all AOE group that has survivability as well as an easy button. Prolly a paladin, priest, and 3 mages/warlocks would be better. Massivly OP in the AOE area, and ballanced enough to take out thoes tough sob's that have the purples.

If you have a good mouse solution for ground target AOE's then I would go with mages. Else pick warlocks.