We have used Dollar mostly(about 18 rentals) Budget once(again in August) and Alamo once and although we had a bad experience others prefer them.
Whichever you use try join their fasttrack service(Dollar=Express) can easily save an hour waiting in line at the desks at busy times, like when a Virgin plane arrives.
We use the 3 agents below to book with, never a problem with any but there are numerous more.
http://www.carhireflorida.net/
http://www.netflights.com/carhire/
http://www.usrentacar.co.uk/