It's just a classic rivalry on so many levels:
1 - Original six vs. original six
2 - Team with most Stanley Cups vs. Team with 2nd most Stanley Cups
3 - Ontario vs. Quebec.
4 - English vs. French
5 - Catholic vs. Protestant
6 - #1 Canadian metropolis vs. #2 Canadian metropolis
Apart from that, I would have to say that I am completely mystified by the Leaf fan. If MTL had gone that long without winning a cup, there wouldn't be a team in MTL. In other words, while MTL loathes mediochrity, TOR seems to blindly support it.