There are three main companies who own the 8 major brands:
Enterprise Holdings:
Enterprise - Last time I checked they had kiosks where you can skip the counter but they like to walk you around the car and give a more hands on experience.
Alamo - you can use online check in and skip the counter. Pick your car from the assigned aisle and checkout at the gate. No membership required.
National - Join Emerald Club to skip the counter and pick your car. You will get you a slightly better selection when booking a mid size car.
Avis/
Budget:
Join frequent renter clubs, Budget Fastbreak and Avis Preferred to skip the counter and go directly to the garage. You are assigned a car but can request another one if you don't like it.
Hertz/Dollar/Thrifty:
Join their frequent renter clubs and skip the counter and pick your car. With Hertz Gold you should get a slightly better selection when booking a mid size car.
So essentially all the major rental agencies have a way to skip the counter at MCO. I would use any of them excluding Enterprise if you want to get in and out quickly.