Tiger dominated golf like no one ever has or ever will - not just winning but winning by sick margins. I think he revolutionized golf by showing that physical fitness has a place in a traditionally lardass sport like golf.
However, I will give a slight edge to Jordan here because he put an entire team on his back and won championship after championship. Think of how good Lebron is right now and then think of what kind of pieces they had to give him in Miami to win - Jordan never had a Wade or even a Bosh, yet he still dominated more than Lebron has or will.
I'll take Jordan in a close one.