Switching my vote to Napoleon. The clincher comes down to Genghis Khan not finishing his military expeditions. Ogedei Khan was the one who made the Mongol Empire second in size only to the British, and he, not Genghis, was the one who so profoundly changed Chinese history and the like in Central Asia. If Genghis finished his military ventures, he would be responsible for more responsible for these things and would keep my vote. "the Mongol theory is to my knowledge one of the least plausible ones" Russia, which was once ruled by the Mongols, had to get their gunpowder FROM Europe. If it were the Mongols, Russia would have had it much sooner. Also, the Black Death thing, even if it were the Mongols who caused its spread into Europe, Genghis had nothing to do with that. It was a century after his death.
Napoleon after landing on the shore of France after escaping exile on Elba to his former soldiers: "If there is one among you who wishes to kill his emperor, here I am."
Genghis: 10
Napoleon: 10