We rented a jeep this last week from American Car Rental. I was a bit leary about it, as I have recently read some thread about them that weren't very flattering.
We actually got a really nice jeep that was in really good condition, and the price was well below any of the other rental companies that I checked with. The first three that I tried to book with had no availability anyway.
The yound man who handled our rental was named Fabian, and i couldn't ask for a better experience. He was prompt, and made the whole experience quick and painless. If you rent from there, ask for Fabain.