I think basketball yields the most athletic players by far for 3 reasons:
1) The better athletes choose basketball over other sports, so basketball has better athletes. Kids like the crowds and press coverage…you see more kids who start playing 2 or 3 sports freshman year, eliminating the other sport and trying to concentrate on basketball. And they choose basketball because it is more fun than getting beat up playing football or getting mauled from behind while dribbling the soccer ball because the high school refs don’t call anything.
2) Basketball is the only major sport where 4 elements of athleticism are important to all positions in order to play well: strength, hand-eye coordination, footwork, and quickness/speed.
3) Basketball players can do well in many other sports. You could take the any good basketball team and you know that most of the players would be stars on the football field. But you couldn’t take the same number of football players or soccer players and have them excel on the basketball court, even if you compared them to kid of the same size and height.
One exception to this thinking is Shaq, who is the most un-athletic player in the NBA, yet may be the most valuable player to ever play the game of basketball. But then again he could just fall down on the offensive line and still protect the quarterback, and could smash the other team’s soccer players and not get a red card.