I would avoid the car companies you listed. Have heard terrible stories about them. We have always rented from Alamo - always fair even if you have an accident like we did.
Okay, go to their site, find the car you want - use codes found in American Casino Guide or "google" codes for them. Check several times a day and you will be surprised how the cost comes down.
You don't have to use your credit card to book it - just keep cancelling and using the new rate. I got my daughter and husband a rate for their trip this month for $325.00. Booked it about a month ago. Kept checking and checking and they finally wound up paying
$133.70!!!!! This was for a week!! Compact car but good enough for them to ride to other properties off the strip, etc. They were thrilled to pieces.
Once you arrive at the airport and get your luggage go out the door for RENTAL CAR BUS and the bus will be there waiting for you. Takes like 15 minutes to the parking garage - head to Alamo area - NOT the counter - use the kiosk and plug away putting in your license, etc.
Refuse insurance, etc. and in no time the printer will print out your agreement - turn around - go up the escalator and find your car!!! Takes minutes!!!!!!!!!!
IF you decide to use the "no name brand" you will be hassled to death for extra this or that which they make most of their money on. Your car insurance and/or credit card will cover the rental insutrance.
We have been using Alamo for over 27 years and NEVER EVER have had any problems whatsoever. The cheaper ones (or so you think) sound good but by the time you are done it will cost you a lot MORE!!!