I can't find all of these, but here are my nominees for Best Moments in Ski Competition.
2007: X Games Ski Pipe - Simon v. Tanner https://www.youtube.com/watch?v=TsKJZyM548E
2010: X Games Ski Big Air - Bobby Brown
2012: X Games Ski Slope - Tommy Wallnuts gets highest score in the event's history
2013: X Games Ski Big Air - Henrik's Nose Butter Triple