Because it is on my route to work, I tend to shop at Sonic Boom more than any other record store in Toronto. It's also useful that there is a pretty fresh supply of used "new arrivals" to check out everyday of the week - so I tend to find things I'm looking for pretty regularly. (Though the "new arrivals" stacks are padded with things that have been there for many weeks, as well - noticing this is perhaps a sign that I stop by too often.)
My only beef with Sonic Boom is that I find new albums to be a bit more expensive here than anywhere else (at least the stuff I'm looking at), when compared to Rotate This, June or Kops.
Despite this slightly higher prices it'll keep being my first stop for used stuff, but last resort for new stuff.