Our Firm just cancelled all corporate AMEX cards and changed to DC. We had a choice before when the Firm provided both AMEX and DC but not anymore.
I did not really mind because I have my personal AMEX and had rarely used corporate card.
I like DC, especially no annual fee since it is corporate card.
I had it before while I was in college (I had a family card issued in Japan). One time they did double-charge to my account. The head of Japan DC in LA came to my house in Pasadena to apologize. That was big surprise but I was so impressed with their customer care. (Maybe the business style between American and Japanese might be different though.....)