For me it comes down to Tiger Woods, Roger Federer, Barry Bonds and of course his airness Michael Jordan. I actully only seen MJ play in his final 3 years in Chicago and his 2 years in Washington, so I can't make much of an arguement for him. Federer has dominated tennis like no other in recent memory, but is still quite young and has only time to get even better. Barry Bonds was always great, but to me everything he has done since '99 is kind of suspect and I believe he took performance enhancing drugs, as well as Clemens. I'll have to give my vote to Tiger Woods, I have follwed his entire historic career, and no man has dominated their sport with a clean slate as much as Tiger has done in golf since the mid 90's.