Both of the swimmers are great in their own place. Spitz was the most successful athlete in the 1972 Olympics. Mark the Shark was the first American athlete to win nine gold medals and the third in the world. His record has since been broken by Micheal Phelps, who won 23 gold medals from 2004 to 2016.  Besides that, Michael has three silver medals and two bronze medals. Although many would consider Phelps a better swimmer considering his gold medals, Spitz paved the way.