Ex-NFL DB Nick Collins -- Aaron Rodgers' AND Brett Favre's former teammate in Green Bay -- says with one more ring ... Rodgers will be the best Packer QB to ever live.
"If he wins the Super Bowl this year, you would have to say he's the greatest," the three-time Pro Bowl safety tells TMZ Sports.
It's high praise ... considering both Bart Starr and Favre are already in the Pro Football Hall of Fame -- but that's how high Nick is on Aaron -- especially after his comeback win over the Bears on Sunday.