Whenever we travel to Europe, there's always a few instances of what we call "card roulette" — where you're standing at a machine (like, say, a Paris Metro machine that doesn't take cash or coins) and you just start jamming different cards into the machine hoping one of them will work.
While many restaurants and shops have swipe readers, there are an inconvenient number of places where you're going nowhere fast without a chip card.
I got a British Airways visa card a couple of years ago primarily because it was the only major US card that had the chip, but that's slowly changing over time. Their card is 'chip and signature' (meaning that you still have to sign a piece of paper for the transaction) whereas most European cards are Chip and Pin (meaning that you have to enter a PIN code to complete the transaction.)
On our most recent trip, the Paris regional machines (pic) refused my BA card (as well as all my swipe cards), yet the Metro machines (pic) worked just fine. I don't think any one card is a silver bullet for the card roulette problem, but I feel like its a much better better item in my arsenal when dealing with fussy foreign card readers.
UPDATE: Barclays now offers a USA credit card with Chip+PIN functionality.