Many years ago Montreal was extremely strong, much more so than Toronto I'd imagine (although whatever Calabrians operated in Toronto were always very low key to begin with).

But in recents decades, between the vast demise of both the Buffalo crew's influence in Montreal as well as the Rizzuto faction having been gutted, I have to agree with Giacomo that "hands down," if I were to cast a vote, I'd vote Toronto.
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** Slight correction: I meant to say, Magaddino (Buffalo) crews "up in Canada" per se, (in general), and the Bonanno crew influence in Montreal, specifically.