I used the AMEX ‘One’ card for years – 1% cash back of all purchases. They deposit exactly 1% of your statement balance in a high-yield AMEX savings account each month.
I just switched to a Charles Schwab ‘Invest First’ Visa that claims 2% cash back, which they place in my brokerage account each month (although I haven’t received the 1st pmt yet).
Both great cards! I’d put my rent on it if I could.