I frequently rent at airports and have noticed considerable more wear and tear on the rental cars lately. I only rent from the major companies and in previous years the cars were always like new. That has changed and the airport add on fees have gotten much higher.
teatime : I always rented on-airport car rentals, in this order of preference:
1. National
2. Budget
3. Avis
4. Hertz
I seldom travel since retiring, but when I do, I use Costco Travel to book my rental car reservations. I go with whoever is cheapest in the place I'm visiting.