I received outstanding customer service at Sixt LAX two weeks ago.
I had really only booked them because the rate on Expedia for that rental class was far cheaper compared to the other companies.

Due to illness, I had to delay my travels by 2 days.
So I showed up at Sixt 2 days late without ever notifying them about this.
My very cheap Expedia booking for a PFAR was not only honored, but the missed two days were simply added to the end (1 week rental total).
Didn't even try to sell me additional insurances.
No hidden fees, no sketchy moves when returning the car.

Like with any car rental agency, it's probably a hit or miss.
In the meantime I now also received my Sixt Platinum card through a Statusmatch. Let's see what that'll change.