Not 100% sure but i think that it is the Indianapolis Colts.
49ers
Tom Brady and Ben Roethlisberger are the two quarterbacks that have the best winning percentage in their first 4 years in the NFL. Ben Roethlisberger has the fourth highest career winning percentage as a quarterback.
Through the 2010 season, it's the Chicago Bears. They have a record of 704-512-42 for a winning percentage of .579.
Pittsburgh Steelers
As of the current season, the New England Patriots have the best overall winning percentage in NFL history, making them statistically the best team in the league.
Among existing teams, the Cowboys have the best winning percentage. As of the beginning of the 2010 season, Dallas is 467-339-6 all-time, for a .579 winning percentage.
the colts have the highest winning precentage
85%
Philadelphia Eagles
Otto Graham was 57-13-1 in the NFL and 109-17-4 overall, the best winning percentage of all time.
bucanners
From 1933 to 2010, the Steelers are tied for 14th overall in the NFL with a .520 winning percentage.