Darth Vader is a brilliant strategist and one of the greatest pilots in the galaxy. Vader still possesses his former persona's amazing engineering skills, having overseen the design of the TIE/Advanced fighter. His talent with the lightsaber is legendary. All of these skills are secondary to his incredible mastery of the Force.
Kyle Katarn won't even come close. People on this forum have underestimated Darth Vader drastically. His lightsaber skills are legendary! And his mastery of the Force is incredible! He believed in his own skills so much he denied to put cortosis in his armor suit (Cortosis is a small mineral that can block lightsabers)
Most of you have argued that he was defeated with ease by Luke Skywalker. No he was not...Luke himself is incrediably strong, and how would you feel about murdering your own son in a duel? Vader didn't do his full potential in any of the duels with Luke. In ESB he was trying to capture Luke and had feeling for him then. In ROTJ he had possibly more feeling for him, because he was picking up Luke's presence as he was on the Imperial cruiser traveling to Endor...which even Sidious couldn't feel. Right there that tells us Darth Vader's feelings on the matter were not clear and even later the Emperor asks him..."Are you feelings on the matter clear, Lord Vader?"
Darth Vader purged all the Jedi, but a few, which provided no threat to the Empire anyway. Kyle is not even close to this great Sith Lord...