I've found that E-Z Rent-A-Car (ezrac.com) is a little hidden gem at MCO (and a few other airports). As a travel agent who uses E-Z as a preferred rental car company for families going to Disney, I regularly see "economy" rentals for $9-12/day +tax and full-size generally only runs about $18-24/day. Add in the 12% off discount for EZ-Money members (2% standard + 10% coupon on their website) plus the 10% "points" rebates and its a really good deal. They also own L&M at MCO, but L&M is typically 50% more expensive because their counter is located in the terminal rather than at the remote shuttle lot.
I used them personally last summer at FLL and got upgraded from a compact to a Mazda Miata convertible. The interior looked brand new and it only had about 14,000 miles on it. That was a nice suprise for my visit to the beach, especially considering I only paid $18/day for it. The other nice thing was that because they are a smaller company, there were only three people in line at FLL, while Budget and Dollar had closer to 50. I just booked them again at LAX in January for $17.00/day for a compact.
Hello! E-Z just opened their new location In Terminal at MCO.
They still offer the same great rates and discount car rentals, and now there's no waiting around for a shuttle. You can go right from your flight to your car.