I don't rent cars very often, but it's always been a pleasant experience.

I have National Emerald Club for free via my Amex card. Any time I need a car, I just click rent from the app on the cheapest car. Walk into the rental lot straight to the Emerald Aisle, pick any car I want (self-selecting my upgrade, I've gotten lucky with convertibles, SUVs, etc.), and drive it off. No talking to anyone. I simply show my license to the guard at the exit gate who records my check-out, and we're done.

I've never experienced anything close to the horror stories mentioned by anyone here.