To be fair, the Habs are a dash of luck away from a cup, and can't get anything but better --- Toronto is the completely opposite, because roster wise they aren't going to get better than they are today.
Let's look at both teams in a vacuum --- if Tavares finds himself wearing Bleu Blanc et Rouge next year, and we find ourselves in the top 5, (god forbid we pull a Jersey and get Dahlin) our team is almost instantly a contender. If Patches can return a decent top 6 RW and a decent top 4 LD, and we can get by without moving Petry or Weber, this team very easily could be scary next year, our draft choice aside.
Drouin/Tavares/Gallagher
Lehkonen/Galchenyuk/X
Byron/Danault/Shaw
Carr/Hudon/X
Mete/Weber
X/Petry
X/X (Some combination of Benn/Alzner/Jerabek/Schlemko/Juulsen)
If come their time to pick, Hughes, Dahlin, Merkley and Bouchard are all drafted, the Habs should look to move their pick for a 'today' player --- and it becomes the Tavares lottery. A player like Tavares, with Price and Weber already in the equation, turn Montreal into an instant favourite, let alone contender --- sure the Leafs will be better offensively, but we will have a significantly better back-end to support a franchise goaltender, neither of which Toronto boasts.