Which No-Fee credit card has the most cash back reward % for ALL purchases across the board, regardless categories?

Credit card companies want your business. I mean, they really want it, and there's a reason for that. Every time you use a credit card, the place you shop has to pay the credit card issuer (the bank) and the payment network (MasterCard (NYSE: MA), Visa (NYSE: V), or similar) stand in line to earn…