As with all things a lot depends on the definition. Lots say a player who could get into any team in the world. Others might say capable of winning a game for a team, or someone who performs in the biggest of games. Others may look to consistency over a period or "numbers" showing up. Me I like the idea of a "wow" factor. Each of the above criteria throws up different names really.
There's little doubt Baines was one of the best fullbacks in the world while here, but he probably didn't have the wow factor of say a Rooney. He also didn't turn up in big games in a way that say a Ferguson, Cahill or Kanchelskis did. Of the teams I've watched I'd probably only say Baines, maybe Kanchelskis were close to being good enough to get in any team in the world.
As for Wow factor, for me it will always be Rooney in his first spell here. The numbers don't really show it up, but beyond the numbers he put in some incredible displays. The fact Manchester United (champions) went in to Alex Ferguson and told him to sign him as they couldn't get near him in a game (in the same way they did with Roanldo) indicates that.
You see the player who broke into the England team in 2004, around better players and the impact he initially had and you saw the all-round player. I'll never forget the home games against Bolton, or that match against Manchester United where he just ran the game. There was one away at Leicester when we went down to 10 men, where he was brilliant as well. Ironically we didn't win any of those games but he was top class.
Lets put it this way,not only did he have a wow factor, but I'd also say that he would have got a place in any of our title winning teams in some position or other.