I prefer Diners although as previously mentioned, it isn't accepted at a lot of places. However, if it if a corporate card for business use, that shouldn't be a concern as most or all travel related businesses accept it. And, if you do use it for personal use for car rentals is that the BEST policy for insurance. They pay everything, you never have to go through your regular insurance company first. Other cards say the will pay the extra after you already go through your personal insurance company. I had to use this option a couple of years ago for a fender bender in Europe. It was so easy! No hassles, no expense on my part. For that reason alone, I would go with Diners IF you plan to use it for personal use on car rentals.