For me its a toss up. I can't decide between Bill Derlago, Bob Manno, Dan Doust or Walt Podubny. I might just have to randomly choose 2 of them and flip a coin, and I'd still have made a good decision.
You could probably qualify that by saying the best Leaf you've ever "seen", but trust me, he's nowhere close to the best Leaf ever.
Some players I never saw but who probably qualify for consideration would be Syl Apps, Ted Kennedy and before them Charlie Conacher who I believe may have been the last Leaf to win the scoring title.
Best Leafs ever (chronologically):
Conacher
Horton
Keon
Sittler
Salming
Sundin
Honourable mention:
Apps
Kennedy
Mahovlich
Clark
Gilmour
Some players I never saw but who probably qualify for consideration would be Syl Apps, Ted Kennedy and before them Charlie Conacher who I believe may have been the last Leaf to win the scoring title.