All of the tried and true leg excercises/lifts should be sufficient enough. What's most important is utilizing FULL range of motion, and not cheating on the lifts. Of all the leg exercises, squats are king when it comes to leg strenth, and endurance. Nothing else compares. What's important to know is that squats aren't all that beneficial of a lift, unless one takes 'em low---to parallel, or lower. Wrap the knees, when going heavy, and ALWAYS cycle weights/reps ((doing box squats is a great way to learn proper technique)). I credit my love for squats as the sole reason that I've never experienced muscle soreness from snowboarding ((not even on my very first outing!!!)).
I lift for strength. I always train with 3 weeks light weight; 20-30 reps. per set, which is known as deloading ((great for recovery, and reset)). In the next 3 weeks, I switch to using a moderate amount of weight; 8-12 reps. per set ((for general endurance and skeletal muscle hypertrophy)). Finally, I finish up with my favorite!! 3 weeks of heavy weight; 3-5 reps. per set ((strengthening the tendons, and ligaments, which is where the bulk of actual strength comes from)). Cycling weights and repetitions is commonly overlooked, but it's usually the reason that people plateau with regard to muscular, and strength development.
I weigh in at 210 Lbs, at about 8% or lower bodyfat. And, even though I'm in phenomenal shape, I'm pretty heavy for snowboarding. But, thanks to my love of powerlifting, and squats, I can literally go the entire distance of a run considerably crouched, when I want to ((which I tend to do, as I ride aggressively)).