There is NO COMPARISON. Jay is known for its trees. Killington is known for whiny New Yorkers. Jay Peak will challenge you at any skill level, and when the sun goes down and the lifts close, you can go surfing indoors.
Sadly, not much open yet, even at Jay. We just spent the weekend at Stowe, and there is no natural snow yet. We have a weekend booked at Jay at the end of January. Should be good snow by then.