Overheard an interesting conversation recently, when it comes to 'best in class' who dominated their respective sport the greatest ?

For example you can not say Messi / Ronaldo / Maradona because there is still not even a consensus on that today.

Many people would say Tiger Woods took golf to a level never reached before? however in terms of career wins Jack Nicklaus still dominates. So I maybe wouldn't accept that.

I heard Wayne Gretzky, is a great example of a single person that was further away from anyone else in their respective sport, however I do not know enough about ice hockey to have an opinion on that.

For me, possibly Michael Phelps? 23 gold medals! Is he the best example of someone who is further ahead of the competition in any sport?