My wife and I recently spent a week at Hotel Plein Sud. We went with Neilson who we have always found good.
The welcome was friendly and all the staff maintained this throughout our stay. The room (north facing) was fine and better than a lot of rooms in ski resorts. Of particular note was the food which was fantastic! A choice of 3 for starter and main and we were not left feeling disappointed once all week. The desserts from the buffet were also delicious.
The ski area in Serre Che is fantastic and pretty big. The hotel is a 5 min walk from the lifts which we didn't find too bad, although we usually felt the need to stop for a beer and a rest on the way back after a hard day skiing!
All in all we were very pleased we chose this hotel and would definitely return.