[Striiker]

I did Unrest instead of Upper Guk for the most part through my teens and into 20's. I love Unrest. It's a spooky haunted house! (When I am at Disney World, the haunted house ride always makes me think of Unrest). It can get crowded there as others have stated and the trains can be interesting.. There is some nice loot and it's an outdoor zone so SOW is always an option.
Upper Guk is a great zone for XP as well. If you go there and there aren't groups available, start your own!