Statistically, Brett Farve
Statistically, Drew Brees was the best quarterback in 2009 and his team won the Super Bowl. I would give him the edge until proven otherwise.
Champ Bailey is statistically the best Cornerback in the history of the NFL.
Statistically speaking the best safety in the NFL would be Tom Zbikowski of the Baltimore Ravens
The NFL has a way of measuring the performance of a quarterback with something called a passer rating. The highest career passer rating is 96.8 by Steve Young. Click on the 'Passer Rating' link below to see how it is figured.
Statistically the Minnesota Vikings have the best Defense