how many days are you going for? are you flying half way across the country to ski park?
Keystone has better trees but breck has better chutes. The windows at key is fantastic but a little on the short side but the outback can make up for that on a powder day. Breck's 6 chair is a good time so check that out.
Also if you are skiing three days you can go check out Vail for a day or beaver creek. both are better than breck or key. if you're here five days you can ski vail or bc twice! skip night skiing, it is the coldest most boring time of your life but definitely check out abasin for the montezuma bowl and east wall. unless you're coming for park then stay away from abay.