No Brainer - Bossy.
And just think - what would have happened if Bossy had had a healthy back?
50+ goals in 9 consecutive seasons (still a record), every season from his rookie year until his last full season, before his last, when his chronic back problems fianlly got the best of him. Retired at the tragically young age of only 30.
If Bossy had a healthy back, Brett is likely looking up from below on the all time goals scored list. So is Mario, Gordie, and even Wayne.
File this with what would have happened if Bobby Orr had had two good knees.