Honestly I don't think France in general has kept up with the level of parks in the rest of the alps. If it has to be France I'd go for Espace Killy, legit terrain and two pretty fun parks in Val d'Isere and Tignes. Problem in France is that the parks often open really late.
For me, Switzerland and Austria is the place to be for parks. Laax is unrivaled, but can have a douchy snowboarder vibe going. In Austria you have a lot of great parks. Serfaus, Mayrhofen, Absolut Park, kitzbühel, Kitzsteinhorn, Hochkönig, Planai, and those are just the bigger ones. You have a ton of more medium sized ones that are just as good, just not as big.
Zillertal is a good bet if you wanna be somewhere fairly central, with good terrain and the possibility of lots of jobs. But Austria is easy to get around in, so you can explore as much as you want.
In Italy check out Livigno for a crazy jump line.