My wife and I have a dozen cards between us and a small business because each one has their own ROI (i.e. almost all the airline and hotel cards, Amex Plat, Citi cards), but several years ago in the name of simplifying the daily decision of what to use 80-90%+ of our personal spend started going to the Amex Everyday Preferred as primary with the CSR in second position for non-Amex places and dining. Main focus was maximizing the transferrable currency return.

In your position I would consider those 2 + keeping your Amex Platinum - but reducing the spend on the Platinum to only the things reimbursed (travel credit/monthly entertainment/walmart+) -- higher return category -- purchases with warranty or travel insurance concern-- or if you have an amex offer for that card not on the everyday. Hear what you are thinking about just the Plat + CSR but that leaves too many points on the table for everyday spend.