Your question depends on what kind of experience you want.
If you want to battle the urban crowds, but have much more challenging terrain, go to Killington.
If you want long uninterrupted cruisers, with fewer people and better flow of people (more top to bottom w/o all the bottle-necks) go to Okemo.
The terrain at Okemo is not that exciting, but it flows well and is good for cruising. mostly Blue square.
Kton will offer more challenge and more miles of skiing, but will also suffer from crowded bottlenecks and simply too many people on the slopes, especially if it is not a black-out time for the seasons pass holders. Sometimes holiday crowds aren't too bad at Kton b/c the cheap passes that everyone has have blackout dates.
If you want to get a feel for the Killington crowd, try
http://www.killingtonzone.com
Try posting your question there.
