It is still possible to farm A3Q1 pretty effectively even after the today's nerf. I just leveled my barbarian from 52 to 53 in exactly 15 minutes by using the following method:
Build
As we know, the mobs won't come down until you have walked the stairs up a bit. So, first you need to go somewhere around...
here. Use War Cry to get some fury.
Use Leap to somewhere in the stairs to trigger the mobs.
Run down and use Ground Stomp to get the mobs to a nice little stack (the mobs just ignore Ground Stomp while moving down the stairs)
Use Earthquake and activate Sprint.
Run to the exit while Eartquake kills the stunned mobs. Leave game. Rinse and repeat.
All you need as a barb are Leap, Eartquake and Ground Stomp, which you get at a relatively low level. And some decent gear. If you perform this perfectly, nothing will hit you so everything you need in theory is a weapon with good damage (not DPS, since eartquake doesn't care about your weapon's speed. Only the raw damage matters). Atleast at 50+ the time it takes to kill all minions is pretty much the same as pre-nerf. War Cry is only used to get fury, you can also Cleave a few times with the +fury rune for it if you want/don't have War Cry.
As a wizard I would try something like this. I haven't tested it, so I'm not sure if Explosive Blast deals enough damage to kill the minions.
This could also be possible with atleast Demon Hunter, using Vault and then AoE'ing the mobs down. Might be a bit slow, tho.
Hope this helped someone, and happy farming!