Bailey does his job well, but I think game winning kicks are what separates kickers.
Whoever has the most game winning kicks is the best IMO.
Anyone have that stat?
Well, that's entirely about opportunities, much more than talent.
As of 2015, the leaders in game-winning FGs in the 4th quarter or overtime were:
Morton Andersen: 35
Adam Vinatieri: 33
John Carney: 26
Jason Elam: 25
Bailey has 11 (he didn't have one last year and hasn't had one this year).
Note that these may include kicks that put the team ahead early in the 4th quarter, not just down at the end, which probably isn't what you're thinking of.
I take that back. In the TB game last year, he kicked 3 FGs in the 4th quarter, taking us from down 20-17 to up 26-20. Not sure if that counts as far as this list is concerned: the last FG wasn't the game-winner.