As others have said, Hertz, Avis, and National are the best if you want to avoid any hidden fees or surprises at the end of your rental.

I've had good experiences with Enterprise in various parts of the country, but that power of attorney clause (in Texas at least) scares me. I read the fine print on rental agreements pretty carefully and have never seen that before.

One thing that bothers me about the cut-rate agencies (Enterprise, Dollar, and Thrifty) is that they take a rather large credit card deposit, $300 or more, when you rent a car from them, even if it's just a $20 one-day rental. I always check my card statements carefully after renting from one of these places, as I don't want the $300 to show up as a charge or give the agency leeway to charge me for damage I didn't do. National only authorizes your credit card for the estimated amount of the rental when you pick up the car; Avis the amount of the rental plus 20%; and Hertz the amount of the rental plus $100. Much more reasonable. I can understand why agencies want large deposits if you're paying cash, but not with a credit card.