Vail(once get away from all the snotty rich people with furs and lepord pants),Keystone,Breck is wack(unless your a park rat)! not very challenging and way overcrowded!!
crested butte has the most challenging terrain out of pretty much all of the colorado mountains, but you have to watch the snow pack cause if vail, aspen and keystone are having a great snow year, cb is usually lacking snow. and when CB has a great snow year the other mountains are usually lacking. this is because cb is on the other side of the mountains and the storm usally go one way or the other