The best selection *by far* is CHS, which operates out of Brampton (borders Toronto to the northwest) - no other Canadian store comes close. I'd be surprised if any of the other stores had even 20% of the stuff this store stocks.
www.homebrew-supplies.ca
It still pays to shop around though, as the prices are often not the greatest (especially compared to American shops, but that's not the fairest comparison). As you start to get more into the hobby of homebrewing though, it's inevitable that you're going to have to buy some stuff from here (and even the American sites), as most other Canadian stores have very little selection beyond the most basic brewing supplies, often little more than some basic ingredients.
Randy, the owner, is a great guy and is CONSTANTLY adding to his inventory. It's quite insane, really. He really does strive to be able to offer homebrewers anything they could possibly want. And that means if there's *anything* you want but can't find, just drop him an email and he is usually more than willing to try and find a supplier for it.
And sort of going off-topic for a second here, but the Ottawa area's local homebrewing club, MoB (Members of Barleyment), is supposedly one of the best in the country and should be able to provide you with some great local info and resources. Heck, I even personally got in on one of their group buys a while back when I bought my Barley Crusher. The link the above poster provided is actually their website, and I HIGHLY encourage joining, for all sorts of reasons.
