Replying to Best Flex for Big Mountain/Freeride Skiing

I'm looking to compete in state and regional comps this year for big mountain, and I'm looking for new boots. Price is no problem, I have an internship at a custom ski shop and have got a shit ton saved up for boots this year. I'm riding 2017 Faction Candide 3.0's, I weigh 115, and I'm 5'6".

I went to go try on boots (Salomon QST 120's, Lange Freetour 130's) and the shop pro was surprised that I could flex 120's no problem. That aside, what is the optimum boot flex for big mountain skiing? OR any other recommended boots for what I'm doing?