I really like Sonder. They are a bit more expensive than the average Air B&B but you get what you pay for - great quality accommodation (at least in the case of their Montreal appartment block), fantastic location, reliability (our bookings at two other MTL hosts were cancelled) and convenient, high quality service - the place was very clean and well equipped.
Two minor issues:
1. On a couple of nights there was noise from a nearby club - quite often a problem in Montreal in our experience. Sonder provided earplugs and an ambient noise device but we didn't use them and in truth the noise wasn't that bad.
2. The TV only worked as a chromecast from a mobile device. Not a problem for us because we are not big TV watchers in general and certainly didn't come to Montreal to sit in front of a screen. But it might be more of an issue if you are travelling with your kids, particularly from abroad as your Amazon/Netflix/etc account may not be accessible from a foreign country.
Overall a great experience and we will certainly use them again.