my favorite is keystone, the jumps are so perfect, and the rails and stuff are all set up perfect too. i really dont like breck that much, the big jumps are all like really huge, and same with the rails, they are all really big or have big gaps on so you have to hit them going really fast and its just not fun. keystone's rails are perfect though. and steamboat is really fun too. but they dont have the best jumps. and vail's jumps are also sweet, but their rails are worse than brecks and just not fun.
so id say keystone is the best, then winterpark.