Never been to Jackson so I can't compare, but I can speak to Whistler since I've been there several times.
Depending on when you go, especially over weekends, it can be crowded so the main lifts can get pretty big lines. However, the two mountains are huge so there is a lot of terrain to explore. I always enjoy riding Whistler even when it is crowded.
The Village can be crowded as well which is good or bad depending on what you are looking for. Like the last post mentions, if you are young and like the nightlife, Whistler can be REALLY fun. I have been to Whistler as a college guy and as an old married guy with two kids (never brought my kids though) and I always enjoy the village.
It can be expensive, but again, depending on when you go, you can find rooms for a decent rate espcially if you are willing to pack a few guys into the room to reduce the costs.
Summary - Whistler can be super fun especially if you want a big ski village experience. Don't go expecting you will definitely get epic powder for days (you might) but go expecting to have a fun trip with lots of other people around with two really big mountains to explore.
Thank you very much for your input it was very helpful. Whistler sounds like the right mountain for me, obviously I want to experience the best riding possible but I also want to have fun at night (Im only 23) and try some good food. Ive never left the east coast for a snowboarding trip so I want to go somewhere epic. The long lines are expected with a big mountain such as whistler and its bearable if I can get some long runs in. One thing I am really looking for are glades, by far my favorite to ride. As per cost I have been finding rooms from $600 - $1000 depending where we stay. I was looking at the Westin but not sure yet, most likely going to use a travel agent for this trip. Overall im looking for the big ski village experience. I was also looking at the size of the two mountains and they are huge looks like it could take a while to get down the mountain as I am only used to riding at Peak and PA mountains.