Thanks for all the advice. I ended up renting at AVIS. I didn't really notice beforehand that the rental car offices are outside the airport and it took me a minute or so to figure that out

The rental experience at AVIS was good, nothing really noticable. It was pretty empty at the time of my arrival (Thursday morning around 11am) there was only one customer in front of me at the AVIS Preferred desk. I received the key within a few minutes and the car was parked only five meters away from the little AVIS hut. I got a Citroen C3 as I rented a compact diesel car. The car was fine, no damage and about 8000km on the dial.

The return experience was ok, very speedy. Only a quick check on the gas, the kilometers and a 5 second run-around the car to scan for damage.

Overall I can recommend AVIS from this experience, the MRS airport though is not really great. Especially the check-in staff and the security personnel were quite slow and not very 'customer' oriented...anyways the nice region in the south of France made up for this.