AFAICT, they both have primary insurance for excess if I can decline CCW?

I'm looking to rebook for an upcoming trip because I had booked with Dollar Rental, which requires proof of credit card coverage. I've heard different accounts of them refusing a premium credit card as such proof, so I guess I can get letters from Amex or Chase.

Beyond that, Amex earns 1X points on the rental while CSR earns 3X.

But for the Amex Plat, it would be part of spending to get 50k bonus, though I can probably get spending without this one rental and potentially another rental for a different trip.