I am required to use Avis Car Rental for all business trips. As a result, I often use them for personal rentals as well since I get free ones. Overall I would recommend Avis. They keep their cars very clean. Definitely join their Preferred program - you can walk right to your car with no lines and the program is totally free. If you do have a problem, Preferred members have a special counter for questions at all major airports. My lone complaint is that they often do not keep the car size I requested. I always want a midsize. However, on my frequent travels to a very heavy use location in California they often give me either a convertible or mini-van, despite my request. This makes me crazy.