Given that Tiger hasn't really left the picture - I'm left with Bo Jackson, Mike Tyson, and Michael Jordan.
The question then becomes are we comparing their greatness in their respective sports back when they were at their best? Or how they would fare against the current competition nearing retirement?
I'd still be inclined to pick Jordan. Boxing has changed, the NFL has changed significantly. And the NBA has changed as well, although I still think Jordan would stand a chance of being more relevant in today's NBA than the other athletes in their respective sports today.