Id say hero, becuase they can easily avoid stuns and seals by standing on body, and they dont struggle with mobs like ranged classes do.
I'd make a case for Night Lords as well. High damage lets you breeze through the arms and body. High avoid and Flash Jump helps you mitigate stuns. Mob control is difficult but still manageable with good positioning (you don't have to actually kill the mobs). Having a SE mule is also a must. Definitely not as easy as a Hero but absolutely do-able.
Hero since you won't need to wash (or just minimally) and you don't need to make an SE mule which can be painful.
The downside with a hero is arm 2. If you're able to solo zakum in a decent time then it shouldn't really matter what class you play since you'd probably be decently strong
It's possible, I've done it several times with my Hero. That being said, my vote goes to Hero. Hero Master Race.
Probably Hero for being able to hit multiple arms in phase 1 and aforementioned avoiding of stun/seal by face tanking with Stance. I'd also give Corsair an honorable mention for being able to ignore summons entirely.
