If you're a park skier you'll have to get one for Big Sky. Big Sky also has the really big fast terrain if the snow permits; if not, then the whole mountain sucks major ass all year and it's really depressing. Moonlight has no crowds, good snow, good hiking terrain and a really crappy layout for the lifts. Bridger has the most technical terrain, the biggest powder days, and the biggest crowds--generally. So it all depends on what you're into and how much money you want to spend.