This is the closest pet store to where we live, but I've stopped in to 3 or 4 stores in Bloor West (with my dog) as well and this one is still the best for variety, helpful staff, and always full water/treat bowls. They have a cat that lays around near the front and is open to being pet despite my ties to a dog.
I recently went in to get some dog booties since the salt was clearly painful for him. The worker encouraged me to open a box and try putting one on my dog immediately to see if they were the right size. I was thankful, both for her thoughtfulness and for finding out that my dog is deathly afraid of booties before spending the money.
Another time we got there (in the rain) just as he was closing up. He let us in so I could grab a big bag of dog food. (Thank you!)
Items are a little pricey, but if you like taking your dog in to a store, this one has healthy food choices, a decent selection of everything dog related (collars, clickers, toys, poopy bags, combs, booties, snacks, etc), and a nice staff.