it's easy to say moorman b/c of the most cash scored online and his fame...I would def put him in the top 5, but that doesn't automatically make him #1.
Here in brazil poker is growing.
And online we are being very well represented with Andre Akkari, Marcelo Fonseca, Bedias, Nicholas Villa-Lobos Caio Pessagno and many others.
From what I've read in online pages, Chris Moorman was and is a very good player online. Although my biggest fear is playing against Argentinos !! And Mexicans! They have with them something called LUCK!
There is no single correct answer to this question. Each of us has his favorite player. For example, I really sympathy to Eugene Katchalov from Ukraine. He is Poker-Pro and play strongly in Live and Online games.
I would say Phil Galfond or Tom Dwan. I think Victor Blom has a lot of game a could school 80% of his competitors but he lacks self control and is horrible with his bankroll. Some players would be toast if it were not for their sponsors or backers.