Like the classic question "paper or plastic?," "credit or debit?" has entered our cultural lexicon, occupying a space at the end of every transaction that is powered by a card. But the folks at Consumer Reports suggest you think hard before you answer. 

According to this research, more people prefer debit when shopping at the grocery store --- especially when  entering a PIN, as opposed to signing a receipt. 

That's good, even though banks want you to choose debit, specifically the signature option. CR says some banks charge their customers for paying with a debit card and entering a PIN. Others offer incentives for signatures, such as frequent flyer miles and other benefits similar to credit cards.

That's because banks bill retailers more for the transaction when you sign rather than punch in the number, in exchange for the electronic magic that goes on behind the scenes.

Debit helps banks make money in other ways as well.