The crappy queen mattress that my parents bought from Sears was a Sealy Posturepedic. My Mom said it started dipping in the middle after 3 days. Like I said before, they aren't big people. Sears had awful customer service!
My parents bought a queen mattress from this website that they still like, going on a year now.
http://www.saatvamattress.com
However, I checked and they deliver to Ontario but only 75 miles outside of Toronto. That is very far from you! They said they will be expanding deliver to more of Canada in 2016.
Sorry, that wasn't of much help!