totally useless question to be honest... not trying to give you a hard time of course... but to go to extremes, for a distance runner, the slight frame is the best human form and the heavey weight weight lifters need the bulk so they also have the best human form.
I would like to see either both Phelps or Bolt do either.
All this talk about who is the greater athlete is also rubbish as if say swimming was as hard on the body as marathons are, there is no way Phelps could have won 8 golds.
In saying that, I do not want to be seen as taking anything away from either Phelps or Bolt.
My favorite sports to WATCH are marathons and tri's as both show incredible endurance and mental strenght.