My English is quite rusty, but everything was still fine.

The service at Avis in Chiang Mai was poor. It took over 2 hours of communication at the counter to get the car, which was very disappointing. The vehicle's condition was okay.

The service at the Chiang Mai location is acceptable. The car we rented likely didn't undergo a major service at 60,000 kilometers, as the brakes were extremely ineffective and almost caused several accidents. Luckily, there was little traffic on the road! It seems the brake pads weren't replaced. We struggled to drive to Bangkok to return the car, but they didn't even refund one third of the cost! Moreover, the service attitude at the Bangkok airport location is extremely poor! Quite disappointed with such a large rental company. Definitely won't choose Avis next time!

The store is easy to spot coming out of the airport, but as others have said, the staff will aggressively recommend you buy insurance even if you already have it, and their English is very poor, making communication difficult.

Like: Got a brand new car above from expectations!
Dislike: AVIS has a pick up and drop off area outside of the airport so it is a bit of a hassle to load and unload luggage on a van that takes you to the place. Same with drop off. Always need extra time..