It takes up more space in my wallet. If my wallet gets stolen then that money I'll never get back. And sometimes it takes up more time when making a transaction.
I always prefer cards. It's nice that all the transactions are recorded for when I'm reviewing taxes and my budgets.
When I had moved to SF my biggest annoyance was how my bank only had a few locations in the entire city. To escape ATM transaction fees I'd either have to haul my ass to one of these faraway ATM locations or get cash back from a store. I could've applied with another bank or credit union, but mostly didn't have to because the convenience of a credit card made mostly solved this issue as I never have to be concerned about how much cash I had on hand.
Furthermore, getting % back on my card is better through rewards than 0% using cash.
Plus if you lose you wallet, or something horrible happens when you have cash, it's gone. There is a bit of a hassle replacing cards, but you don't just lose your money.
* Both coins and high-denomination bills can be and have been refused by brick-n-mortar stores (not all or most but they are within their rights to refuse it as payment).
The strangest part of my recent trip to Canada was places using cash. It was odd having that bulky stuff in my wallet, I haven't paid in cash for at least 5 years, for anything.
However, New Zealand has the world's largest use of card based payments - everyone takes cards, from the supermarket to the food trucks which are just taking off here.
Credit cards aren't widely accepted though, because of the fees. The bulk of the transactions are via EFTPOS, which has low to no fees for both parties.
Cash.