i believe i used Costco when we did a one way rental in PC. keep checking their prices. for an upcoming trip, i booked with them then a few weeks later the rates were even lower so i rebooked.
Once you have a rental from Costco that you're happy with, go to that company's site and price compare. I know on Alamo, you just add the contract id for Costco in and they match or better the price, especially if you are a member of their rewards card (ie: Alamo Insiders). If not, keep the Costco rental.
I love National. At MCO, they have the emerald aisle. You rent a midsize, and get to pick anything out of the aisle. I usually get a Chrysler Town and Country from MCO. You walk to the car, drive out. No lines. You will have to sign up for the club, but it is free.
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