Although some areas claim to be larger, they just can't compare overall. I have skied there on three winter trips and once in the summer. Americans booking a package plan sometimes avoid Val because the prices are higher, compared to Chamonix or Innsbruck, but it is worth the extra cost.
Snow conditions are always good in the winter, even when other areas are starving for snow.
If you can't go in the winter then visit in the summer. You can ski in the morning on the glaciers and swim or golf in the afternoon. Don't miss out. Everyone should try Val d'isere. You'll go back again and again.