The phrase "The next decade" instantly renders any prediction useless. A decade ago the best players on either team hadn't gone through puberty. Proclaiming one team's future to be better or worse based on players who are currently 11 or 12 years old is kinda' silly, no? Predicting five years ahead is pointless; 10 years is ridiculous.
As to the question, Toronto looks built for Right-Now. Management appears to be going all in because they understand how short these windows are. If they manage to win a Cup it'll be nice for the older fans who've waited a lifetime, but they'd better do it soon. The NHL is littered with on-paper champs who could've won, but didn't. Their impending cap crunch won't kill them, but it's fair to say their roster won't be as strong once they're forced to start jettisoning key contracts.
Montreal is in their beta phase, with zero expectations for this season. They've got the youngest forwards in the league and a group of top prospects a year or two away. Their incoming talent should begin to tilt the board in their favour in two/three years, but of course there's no way to predict how good those kids will be. As a Habs fan, I'm more interested in watching this new team evolve than I am in looking ahead to Cup windows. They'll be a contender soon enough, but the process of actually winning a Cup is not as formulaic as some believe.