I think it depends how you define "best". Genius is probably one of the most if not the most talented players but he hasn't played that many HU SNGs and doesn't seem to focus on them very much. Dario is the most aggressive and when he's running good and playing with confidence, he is probably the most dangerous player. There is, however, a wide range in the quality of his play and when he isnt playing well, he can give a lot of money away quickly, as evidenced by his crazy sharkscope graph.
If you had a series of HU SNG tournaments of the best 30-40 players, the most consistent winner might very easily be different from the player with the most earnings or highest roi. There are different skills involved here. One of my best qualities I think is my ability to adjust very specifically to my opponent so if I'm playing a bunch of very good thinking players who are constantly trying to adjust to me, I'm not sure I have a big edge. But in terms of exploiting weaker players, I think I do that better than most players and therefore beat weaker players a higher % of the time; even then players who are considered very good. This is a skill that many cash game players lack and even look down upon in "tourney donks" - I have been called bad at "real poker" more times than I can count. From a specific strategic standpoint, I think the best HU SNG players tend to be the ones with MTT backgrounds rather than cash game backgrounds.
I only really play on Full Tilt and the best players there are getmoneyobv, amak, plz stop lookin, wag dodge, purecash25, nordberg