I say fighting. it's based directly on you and your skill. like golf. not much randomness involved.
combined with execution, accuracy, memorization, quick reflexes, mind games, high dexterity, timing, and having to switch up your strategy on the fly like within seconds to turn a match...etc I say it takes the most skill.
See The Game Collection http://www.gamespot.com/users/nights_team2k7/games_table?mode=own