Going by the poll it seems like Grimrail Depot is by far and away the favorite, with Iron Docks as the far away second, and Everbloom and UBRS as the runner ups.
Never got the appeal of Iron Docks, but I have been told it's the favorite dungeon of many, so shouldnt be a surprise.
Hopefully this trend keeps going and it isnt just a case of the most fervent believers in Grimrail Depot voting first.