Hard question
When I started this thread I knew that it was a hard question.
As some of you had mentioned It's not just a matter of numbers and I chose an old guy (Enzo), because almost always the history tell us the truth.
I met Umberto in my Island and he's a wonderful person, his achievements in freediving are superb, and it will be interesting to know his opinion on this thread.
I name the poll the greatest freediver of all times, to point out that it has to be a person that give a lot of his life to our sport and also made incredible things.
When I read the story about Enzo braking the 50 m "limit", I just think this is an amazing person. Remember that the "Big blue" was a movie, and Enzo wasn't like he was showed.
All of this is to say that at this moment I think we have great fredivers: My brother, Eric Fattah, Seb Murat, Manolis Giankos, etc that are not included in the list. The history will give them it place.