Brilliant player no doubt, but wait until he's been retired a few years to see if he's the best ever. The 2011 Lockyer wankfest got pretty sickening at times but since then his legacy has lowered a fair bit. Nobody really talking about him as the next immortal or how his team struggles without him. Thurston is similar in the 2nd regard too, the Cowboys have been as good without him this season as they were with him and Queensland in Origin 3 did fine without him.
I'm obviously bias but Johns is the best I've seen. He had more affect on the result of a game than any player. Smith is closer to him than Lockyer and Thurston because like Joey he's dominant on both sides of the ball. The rabble that my club has become since he retired as well as NSW having won only 1 series of 12 since he finished up is a testament to how much they relied on him to win football games, not to contribute to, but to get the result almost single handedly. I can't imagine any player past, current future having that level of impact on the teams they play in.