Again, the best defensive player I HAVE EVER WATCHED PLAY would have to be Rod Woodson. The guy was amazing, not only was he the cornerstone of some great Pittsburgh Steelers teams, he was a pro bowl defensive player on every team he ever played for.
1. 1987-1996 Pittsburgh Steelers
2. 1997 San Francisco 49ers
3. 1998-2001 Baltimore Ravens
4. 2002-2003 Oakland Raiders
He went to the Super Bowl on three of those four teams and the 49ers were a very competitive team the year he played there as well.
*HE PLAYED IN 11 PRO BOWLS (a record for a defensive back)
*HE WAS THE FIRST PLAYER TO EARN TRIPS TO THE PRO BOWL AS A CORNERBACK, SAFETY, AND KICK RETURNER
*HE WAS THE AP 1993 DEFENSIVE PLAYER OF THE YEAR, AS WELL AS THE UPI AFC DEFENSIVE PLAYER OF THE YEAR
*HE WAS NAMED TO THE NFL'S 75TH ANNIVERSARY TEAM (top 100 players of all time list)
*HE'S ALSO A MEMBER OF THE 1990'S ALL-DECADE TEAM
*CAREER LEADER IN INTERCEPTIONS AND GAMES PLAYED BY A DEFENSIVE BACK
Rod Woodson also holds the record for most interception yards and most interception touchdowns. He holds the league record for interceptions returned for touchdowns with 12, and is tied with 11 other players for the record for most fumble recoveries in a single game(3). He had 32 career fumble recoveries.
And more importantly than any of his stats, was his leadership ability. He was a natural leader for any of the defense's he played for.
This was a tough question and the homer in me really wanted to say Bruce Smith, who has the most sacks in NFL history with 200 (yes, even more than Reggie White) But I just had to give props to Rod Dog, b.c. I feel as though he's always overlooked when talking about the greats.