We rent cars fairly frequently for little day trips since we don't have our own. I've shopped around and think Enterprise has fairly competitive prices. I also think the service is superb. I've never had to wait long, the cars are parked right next to their office, and when you return the car, and they ask you "how was it?", they really want to hear your answer. I've found that if you say anything about the car, like "there was a funky smell", they'll give you a discount on the rental. Also, one time I filled the gas tank too much, and they gave me a discount on the extra gas that was in it. Now that's what I call service!
The only negative is, you can't drive their cars into the US. And also, that one time, there really was a funky smell. I had to keep the windows down.