All good heating system designs starts with room-by-room heat load calculations at realistic indoor and outdoor temperatures, then adding them up to find a whole-house value. The 99% outside design temperature for Montreal area is between -24C/-11F and -22C/-7F. Most people use something between +20C/68F to +22C/72F for the indoor design temperature in making those calculations.
"Well insulated" is a meaningless description from a heating & cooling design point of view. The exact construction type, insulation type, and R values are necessary for making the heat load calculations, as well as the U-factors & sizes of the windows & doors. Include the foundation type & insulation too.
Also, what are your fuel options? (Natural gas, propane, oil, electricity, wood, wood pellets?)
Without the heating & cooling load information, there's no telling what a "best" solution would be. It's rather like asking, " I live in Montreal, and will have a skateboard in my car- what is the best car for my situation?" The answer to the car question will depend on what else needs to go in the car, how fast/slow it needs to go, and what sort of minimum fuel economy it needs to get.
So, let's start with estimating the heat load- how is it built, and what are your R-values/U-factors?