I would have to say stay in the village. They are both VERY close to the lifts...however in the village you do have a few more lift options. There is also more to do in the village; bars, restauraunts, ice skating, etc... copper station has a few restauraunts near it, but most are in the village. There is a free bus that gos between both areas, so you really can't go wrong either way. If you do have to be there during the holidays, sign up for the bee-line pass. It gives you a special line in the lift maze that has much less of a wait if any. it might only be available if you book your room through copper reservations. Also if anyone in your group will be needing gear, make sure you take care of that when you first arrive, not when everyone is trying to rush to the first morning of skiing. It can be very busy in the rental places during the holidays, I have seen people wait for hours in line trying to get gear at 9:00 am. Try to get there in the mid afternoon or late evening. the crowds are not as bad then.
I hope this helps