Blue Mountain in Ontario is a pretty safe bet, but in all honesty Quebec offers way better snow. A couple friends and I went down to Mt. Tremblant last season and had a great time. There are a ton of other Ski/Snowboard resorts within that area, probably 20 to 30mins apart, so if you lodge in one area, you can definately go to another the next day. We tried Tremblant the first day and then went to Mont St Sauveur the second day, it was less packed and the hills there were great.