My sister & I are planning to rent a car while in Aix-en-Provence in Oct. My choices seem to be Avis & Sixt. Is there a preference? Renting a car in Europe & driving there is a new experience for me & I would like it to be as trouble-free as possible. We will be renting in town rather than at TGV station as we only need it for a few days. All opinions would be helpful.