I've had good experience at my local Discount Tire, but then there's a couple of Jeeple working there too. It's the guy running the machine that makes all the difference in the world. If they know what's needed and are motivated to do that it makes all the difference in the world.
Surprisingly I've never had any issue with the Discount Tire on 185th in Tanasbourne. They've always mounted and balanced my larger tires without issue.