For self-driving in other European countries or places where you understand the language, any car rental company is fine. However, for self-driving in the US, I found AVIS to be the most reliable, though Hertz is also good but tends to be more expensive. Compared to Hertz, AVIS offers better value for money. The cars are new and come with Easypass, so you don't need to rent it separately. Some companies seem cheap at first, but when you add the Easypass rental and other hidden fees, the total cost is much higher than AVIS. The return process is very simple, and the service is very patient. I'll definitely choose them again in the future.