Now that I've used them a few times, I've come to notice I've had more issues with cars rented through Alamo than the others. In Maui last year, the car we were assigned was dirty inside and not washed well on the outside. The second car (an Impalla) that replaced dirty car was fine. In Sacramento I had no issues with the Malibu we had for the weekend.
Now here in HNL, I returned this afternoon the car we picked up Saturday. This was the second car, the first a Malibu wouldn't latch it's trunk. Car two was a Buick LaCross and had a check engine light on since Sunday. Customer phone service had us open, remove and replace the gas cap. When that didn't change anything they told me I had the option to continue driving it or return it. So long as the light wasn't flashing, I was ok. Well the car drove fine, but the milage stunk (15 MPG), so we brought it back late this afternoon and exchanged it for a Saturn Vue mini-SUV. My kids are happy and so far so good. Again, I can see where they did a slap dash cleaning job on the inside before returning it to service.
In contrast, our rental on the Big Island with Buget was just fine. Likewise I've had pretty good cars with Budget in Las Vegas. Customer service wasn't always great in Vegas, but no problems with their cars.
I've not rented from Dollar in several years and don't recall issues with them. Alamo seems to consistently have the best rates through Costco that I've seen.