You are looking for a medium flex binding given that you intend to use them for all mountain and park. what is most important about a binding is fit and comfort. I'll assume you have a big boot since you are riding a wide board. If so, I recommend the Union Force in L/XL. This binding fits big boots very well. In addition, the Force takes up the smallest footprint on a board given your boot size. This means you'll minimize your flat spot under your bindings and have better board flex. The heelcup is adjustable so you can dial in your stance.