I've never been a Dollar fan. If the rate they offered was quite a bit lower than the rest I would use them, but that is not common in my experience.

Avis, Hertz and even Budget have been very good service and handling my car rental needs.

That being said, seeing as travel is now on my own company dime, I use Priceline for most of my car rentals. More than likely your company will not allow use of Priceline.