My recent experience with Avis is a clear case of why you can never let your guard down.
Despite having an agreed-upon reservation time, I was left waiting for an hour before being assigned a vehicle. When I finally got the keys, to my frustration, the car's fuel tank was completely empty, forcing an immediate, unplanned stop at a gas station before I could even begin my trip.
The most aggravating part came after return because I was hit with a $135 Fuel Service Fee. It was an incorrect charge that felt like a betrayal after the initial hassles.
To their credit, after I filed a detailed complaint and provided my well-documented time-stamped pictures of the full fuel gauge and receipt, Avis did the right thing and withdrew the fee.
Final Verdict: You can use Avis, but my experience shows that trust is not something you can afford to grant them. Verify everything at pickup and return. Take pictures and keep all your receipts. Without my evidence, I would have been out a significant amount of money for their mistake.
Recommendation: Don't Trust, Verify!