I was joking in my original response. This time, I'll address your post sincerely. I'm cool with Toronto and with Torontonians. In fact, I've posted here that if the Bills should leave Buffalo, the only way I'd continue to root for them is if they moved to TO.
Aside from a good natured rivalry with a team that's 90 minutes up the Q, my dislike for all things Leafs stems from the attitude that many of their fans (not all, but many) seem to have: As an American, I can never fully understand the game and cannot possibly appreciate their passion. Never mind the fact I learned to skate at the same time I learned to walk. Never mind my parents' first date was at a Buffalo Bisons' AHL game. Never mind that my grandmother couldn't watch football because she was unable to follow the ball but never missed a home Sabres game. Never mind that I was raised in a family that embraced the unique culture of the game. Never mind that I grew up playing both shinney and club hockey. Never mind any of that because as an American, the game couldn't possibly mean as much to me as it does to them because their family is from the other side of the line on a map. And Lord knows, I certainly can't ever know as much about the game (or even more - gasp!) simply because they're Canadian. And not only are they Canadian, they're Leafs fans - as in Original Six Leafs - to boot!
The proximity to Bflo and the holier-than-thou attitudes are the reasons I dislike the Leafs and many Leafs' fans. But that's just my take. And while I'm sure there are many Sabres fans who feel the same, I'd bet a Loonie that more are just ol' fashioned xenophobes.