I've been going to Duff's for a few years now, and I am baffled by comments stating the wings are small. Where do you buy YOUR wings from?! These are some of the larger wings I've see in Toronto.
These guys specialize in heat. I've had sauces from Medium to Armageddon, and I prefer the Medium-Hot, or Hot. I find that's the perfect balance of heat and flavor. I've tried a couple of the mild flavors as well and they decently good.
Not the cheapest wings in the city, but you do get a solid bang for your buck!