The three "S's" are all pretty good. Sealy, Simmons and Serta. Kingsdown is manufactured here in Ontario and I happen to have a set from Kingsdown. Good quality, good price and very happy. I believe Kingsdown might be right in Toronto at the 400 and 401? I could be mistaken.
In any event, beds are like bikes. What's good for one person isn't always the best for another. Where ever you go, ask about there return policy. Most have them but, they do vary. You might like it in the the store and after a week, want to return or exchange it for something else.
Most big stores have their own specific "models" if you will so, you can't price compare. The Brick with have their Sealy 2000 but, Leon's has Sealy 2200. Same bed, different pattern stitch on the top or different color material, same internals, contruction etc. Price differences can vary depending on volumes sold.
Sleep Country has good prices on bedding. But, they kill you with everything else so be careful there.
Finding good quality, knowledgable staff in retail is always a challenge but, I do know a few I can recommend at Leon's if you tell me which store you want go to.
I don't work for Leon's. But they are my customer and I know most of the staff at all their stores across Canada. PM me if you want more details.
Cheers.