During a recent trip to the USA I used both the Marriott Rewards credit card, my American Express card and my Lloyds Bank Avois Cred card to pay hotel and restaurant bills.
The exchange rate for the Marriott Rewards credit card was on average 5 cents lower than both the other cards. I called Creation and asked them to explain and was told it was to do with the rate charged on the day the transaction was made. This is nonsense since the difference in exchange rates over the course of 20 days was the same.
Amex rates on September 12th was 1.57 to 1.60 on Sept 23rd
Lloyds rates on September 17th was 1.59 to 1.61 on September 30th
Marriott rates on September 13th was 1.54 to 1.56 on September 29th
The transaction fees also look higher than other cardsd