I have had the best luck with Enterprise. They aren't the cheapest, but they have always had the car I ordered there when I got there. Hertz is good too. They haven't always had my car, but gave me an upgrade when they didn't.
Last few years I often visit Toronto for business, and from the first time I have tried https://iversta.com/ I
use only this service. More then 5 times I used it and never had any
problems. It's easy to find car I need, it's cheap, cars always clean in good