First off, this is a very complex question and also worthy of discussion - Dave Starman is right, you could spend a lot of time discussing this subject. So who is the best "American" hockey player? The first question I would have to ask what position are we talking about? You could break it down by postion - you have forwards, defenseman and goalies.
Another question is what time period are we talking about? You have the present time and the how far do we go back? Do we go on pure statistics?
The game of hockey has evolved due to technology and hockey isn't like it was back in the 1960's and 1970's.
Right now in my opinion, I think that Zach Parise is one of the best American forwards in the game of hockey there are other players you could include in that conversation. Pure statistics - the all-time top scoring American forward is Mike Modano with (561g-813a—1374pts).
This past season, Phil Kessel was the top American born hockey players for the 2011-12 season with (37g-45a—82 pts) and Zach Parise was second with (31g-38a—69pts).
In goal I would have to say that Tim Thomas, Johnathan Quick and Ryan Miller are pretty good but so were John Vanbiesbrouck and Tom Barrasso.
Defensively, Phil Housley is the top scoring American born defenseman all time with (338g- 894—1232).