JM is well known in Montreal but gets a lot of competition from Desautels, McGill and HEC. I've lived in Montreal for a decade but never heard of Tefler. Outside Montreal and within Canada, I won't rely much on JM's reputation to play in your favor over Desautels's, Rotman's or Ivey's reputation.
Montreal, unlike Ottawa, is a very dynamic city, full of things to do and an amazing hub for entertainment and festivals. Ottawa is where our government lives, so it's has this typical political cloud that hovers over it. Like Montreal, Ottawa is great for families. So it all depends on your lifestyle. Cost wise they are about the same, just more taxes in Quebec.
Language: It's good to know French in Ottawa and especially in Montreal, as you can increase your recruitment opportunities. You can always study the language during your MBA or just start from now.
The question is where do you see yourself in the future. Aside from the fact that anything could happen and that risks might play out in your favor, do you want to stay in Canada? Do you want to move later to the US? Do you want to live in QC, ON or move all the way to BC or AB?
Go for JM if you want to stay in Montreal.