Notwithstanding Hayne, Dugan and Locke are the most promising fullbacks in the game....Personally, I think Locke is the better player, on account mainly of the fact that he's more a natural ball player than what Dugan is, and the fullback in today's game is becoming more and more of a second 5/8....Josh Dugan is an immensly talented footballer. I just think that Locke is better.
In terms of other players, have a look at Will Hopoate from Manly (although I think that he'll end up on the Wing like his dad), Gareth Widdop (who could be everything that Dugan and Locke are becoming as we speak) and Jake Mullaney.........
But it'll all come down to who wants it the most...