What stuff you want to ski?
Killy has decent park, good bumps, good terrain, lots of snow, good steeps.
Mt Snow has good park, and thats about it. Relativly flat Mountain, some steep on the north side, but nothing to get excited over.
Okemo has ok park, and flat terrain everywhere.
Not sure on pass prices at Mt. Snow or Okemo, but I have a Killy College pass and it was like $340 or something around there. If you are over 18, not a student, then you will get raped on a pass, unlimited pass at this point is prob. like $1200+