I know i haven't confirmed and have just jumped onto this thread, but I would highly recommend Val Thorens from past experience, even if it means you get slightly worse accomodation or pay a little more.
Les deux Alps - I never liked, it felt small & you need to get right up top to get any decent runs. The others highlighted I haven't been too.
I personally like going to the big multiple valley resorts, if you get the full pass you can make some nice day trips right across the resort, with that in mind Val Thorens, Courchevel, Meribel would be good for les 3 valleys - I think Meribel should be cheapest (Courchevel is where all the Russians stay and is pricey), Val Thorens I didn't stay in, but have boarded in the area.
The other big one is Paradiski- Les Arcs, La Plagne, Vallendry - I stayed in La Plagne for a week once, but to be honest that resort seems to have a shit load of traversing and it's a bit of a pain on a snowboard
I would be wary of smaller less well known resorts, you can arrive to find the piste area is very small & in case conditions are not good you want to find somewhere that has a good mix of high & low areas facing different directions.
The other place I love to go is just to hit Chamonix, you can pretty easily do this w/out paying through the nose for a package, book some low cost flights to geneva, book a chalet / apartment for the week, get a couple of hire cars and tour around the different piste areas - Chamonix has some very nice easily accessible off piste too.