If you have all the enemies standing within 8 meters directly in front of you, Templar works out the best with either jabs or sweep spam. Though I think if you weave the skill between lightning staff heavy attacks it diminishes the damage

For the least amount of effort, if you would rather use the least number of inputs and you’re not in the mood to chase after enemies, Warden has subterranean assault hitting a 20x7 meter patch of ground in front of you two times per cast. Recast it every 6 seconds for maximum effect. Probably pretty good with a lightning staff

For more effort Necromancer can summon blastbones to launch and damage a 6 meter radius, but sometimes the summon will stand around rather than blast when the target you selected dies prematurely. Sometimes you have to wait 3 seconds to recast, sometimes 4 if it’s moving towards to a target far away it’s more of a headache

Those skills listed above are the class defining AOE skills that tend to do the most damage on a fight report. But every class tends to have an AOE DOT skill or two

I tried every weapon playstyle in the game, lightning staff heavy attack builds seemed ok for AOE but I think it’s behind melee weapons and bow, and probably even lightning staff light attacks between AOE spam skills, I’ll have to try that eventually

I think lightning heavy attack splash damage covers a 5 meter radius around the target, every light and heavy attack from 2H also does that

But my own personal favorite in dungeons is a warden archer build: Subterranean Assault, Endless Hail, Winters Revenge, Mystic Orb, Acid Spray. Everything in front of you within 20 meters goes down pretty fast, even the mobs that run away, you don’t even have to move. The bear picks up some of the slack, too, it’s usually ready to swipe the last mob standing when you hit the ultimate button

Thanks for the responses so far. Giving me a few ideas. I play a warden currently, and most the build is built around AoE/DoTs. I like it, but wanted to try something new.