Hello all. Im a 26yo male who's looking to rent a car for the first time on an upcoming trip to LA. I currently carry the CSP, Southwest, United and Arrival+ cards. I know each one has some sort of car rental benefit, though without ever renting a car, its hard to understand what is actually useful.

If you were looking to rent a car and carried these cards, which would you use, and through what portal/website would you book to get the best deal/perks?

Thank you from a complete newby.