Of the players that I have actually seen play (the likes of Sterling and Mortimer on video of course).
There have been so many bloody good players that its really really hard to name a single player.
In terms of sheer genius in terms of ball playing skill and creativity etc I'd say Andrew Johns with Darren Lockyer coming in a close second....but then again how bout Sterling or Mortimer or even Langer?!
In terms of intimidating yet fair and respectable forward play I'd say Gordon Tallis or Shane Webke.
The best all round player I have ever seen play though would have to be THE KING!!! WALLY LEWIS!!!