I can really recommend La Plagne! It's good for all abilities, you can also ski Les Arch and it's not overly expensive like the three valleys. We went the first week of Jan and the snow was amazing and was pretty quiet. It's also got some good bars for a few beers in the evening! The scenery there as well is stunning! The only thing that was great was the transfer to the resort (which was 3 hours ) as we flew into Geneva but you can fly to Chambery which is only 2 hours.
I want to go back!!!