I use a Canadian Mastercard to pay at restaurants, etc. while on vacation.
As a example, I recently made a transaction in Dubai, where after inserting my card and entering my PIN, I was asked about whether I wanted to proceed with the transaction in CAD (Canadian Dollars) or AED (Dirhams).
Should I pick the local currency or the currency of the country where the credit card is issued? Is there a substantial difference in picking one over the other?