There are several players I could list, since your question asks for the highest stats. Those stats could be for a quarterback, running back, wide reciever, or any other position. Do you mean most yards rushing, most yards passing, most yards receiving, most touchdowns, most quarterback sacks or other statistic? Since you weren't specific, I will give best players at the main positions according to records.

For quarterback, I will list the players with the most passing yards and most touchdowns. Brett Favre has the most passing yards of all time with 70,520 and most touchdowns with 504.

The leading rusher of all time is Emmitt Smith with 18,355. He also has the most rushing touchdowns with 164.

Jerry Rice leads all wide receivers with 1,549 and most touchdowns with 208.

Bruce Smith leads all time in sacks with 200, although Reggie White has 198 in less games and is widely regarded as the best defensive end of all time.

The defensive player with the most interceptions of all time is Paul Krause, with 81.

That depends on how you define greatness. Are stats alone sufficient? What about Super Bowl rings? Should that count? What about MVP awards? All those are good ways to define greatness.
Super Bowl rings are the best to me, and that leaves us only two. There may be a third that will join them at the end of this season. Terry Bradshaw lead the Pittsburgh Steelers to four titles in the 70’s. He lead a team that included Franco Harris, Rocky Bleier and the Steel Curtain defense.
Another candidate for the best ever would be Joe Montana of the San Francisco Forty-Niners. He led his team to four Super Bowl titles as well. He is also famous for The Catch, a 15 yard pass to Dwight Clark that defines an amazing finish for a football game.
Tom Brady has three rings. He may join the club at the end of the 2010 season, as his New England Patriots are the best team in the NFL and are primed to win again.

Diego Maradona...i juss love him...!!