this is a discussion. you can agree or disagree, but the facts i present are facts, not opinions.
according to the New Oxford American Dictionary, an athlete is "a person who is proficient in sports and other forms of physical exercise, specifically an athlete is defined as "a person who is skilled in competitive track and field events (athletics) - the sport of competing in track and field events, including running races and various competitions in jumping and throwing. but history has slowly adapted the definition of athletes and athletics.
a skier is a person who skis. a field hockey player is a person who plays field hockey. a football player is a person who plays football. a gymnast is a person who does gymnastics. a soccer player is a person who plays soccer. a volleyball player is a person who plays volleyball. a tennis player is a person who plays tennis. the list of sports can go on and on. basketball, bowling, fencing, hockey, swimming, wrestling, baseball/softball, golf, lacrosse, ultimate...
recently, as in not ancient greece, athletes have been defined by a list of characteristics that track and field athletes of the past exhibited. essentially, a true athlete in today's world is faster, stronger, higher than his competitors.
so by definition, the best athlete would be either Michael Johnson (400m), David Rudisha (800m), El G (800/1500m) or Haile Gebrselassie (1500/Marathon), with Kenenisa Bekele in a second tier.
now, everybody is going to complain, but the facts are facts. if you want to say a runner is wimp, look at some bigger guys like Alan Webb, who is probably stronger than your average D2/D3 college football safety. in fact, it has been tested and resolved that on average, track athletes are stronger than football players, based on pushups, bench press, and squats (now you are faced with discriminating between a qb, rb, wr, o-line, d-line, lb, cb, safety). also look up chris solinsky. at 6-1, 165 pounds, he is a behemoth on the track. this dude can run 4:23 miles for 6 miles, 4:15 miles for 3.1 miles. and this guy is a jacked mofo.
now for opinion, the best athlete would either come from cross country skiing, gymnastics, 5k-10k runner pool, or a linebacker.