Here is a list of some of the car rental companies in France. As with any product, I suggest you shop around to try and get the best price. So along with car rental companies I'm including a link to Auto Europe, a car rental consolidator. They can at times be cheaper than renting directly through a rental company.
I'm also including a link to Renault Eurodrive and Buy Back Cars with Peugeot programs that can save you money if you rent for longer than two weeks. Both are only for those who live outside the European Union. In short you buy a new car and then sell it back when you are finished with your rental.