THIS IS a fantasy wish list so to speak...right? Why do we need only 4 heads? Chief.....
There has to be a cut-off at some point. That's why this is such a hard debate. Chose only 4.
Of all time, I say...
Ali
Jordon
Babe
Jack (until Tiger surpasses him)
All of the above names are known on a 1 name basis. Their faces are as easily recognizable as their accomplishments to their respective sports. BTW, you could easily make a case to substitute Jack out for Gretzky.
On a side note, I find it interesting that in America's #1 sport (NFL), I found it very difficult to come up with one standout representative. Is their a consensus "best player ever" in that sport?