randall cunningham
One of the most underrated QBs of all time. Played for the Philadelphia Eagles most of the time but also had stints in Minnesota, Dallas, and Baltimore before retiring.
The closest he ever came to a Super Bowl was in 1998, when he led the Vikings to a 15-1 season. The team made it to the NFC Championship but they were beat in a heartbreaking game that ended in an OT field goal to the Falcons. Randall Cunningham never played quite the same afterwards.