We've been to the US 3 times, and every time we have rented a car through Alamo as they had good deals for us. We live in Norway, and has booked directly on Alamo's site, and through our travel agent. Every time we've got a deal with 3 drivers, a full tank of gas and a gps. And according to our travel agent, Alamo is apparently cheaper than many other rental car company's in Florida in his experience. Don't know if the deal is valid when booking from other countries though.
If you look on www.mousesavers.com she offers many discount codes for the companies in the Orlando area. Also it makes sense to ask in the Budget Board but the best rental car deals are usually discussed on the Transportation Board.