We've always used Auto Europe a couple of times before without any issues. However this year (also France) Elephant Car Hire came out cheapest.
Watch out for the excess insurance issue i.e. Standard insurance hire usually has a huge (~1000 euro) excess built in. They always try and flog extra insurance to cover this when you pick the car up, often at big price, however you can buy excess insurance from a broker here for around £40 a year. Whether you are bothered about taking insurance to cover the excess is another matter!