They are both pretty dominant, but I have to go with someone else.
Ben Askren NCAA wrestling champion. He is 27-0 with 23 pins. In one astonishing stretch, he pinned 15 consecutive opponents in the first period. The guy ranked second at his weight went down twice in a 19-day span, in 2 minutes 34 seconds and 2:16, respectively. All-American Matt Herrington of Penn lasted just 39 seconds. Plus his winning streak stands at 72 right now.
Oh and he has way sweeter hair than either Tiger or Federer.

You have to be kidding.
Wait 'til the kid does it four years in a row like a few others have done.
LOL.
Then, he'll leave college, get fat, and sell cars.