I guess it depends on the fees charged by your bank. I know in the UK some banks charge a £1 "non-Sterling fee" every time you withdraw money from a cashpoint in countries that don't have the pound as official currency (i.e. 99% of this planet), while such fee doesn't exist when using your credit card.

I'd first ask for the exchange rate at the transfer company desk. Perhaps it's better than the one offered by the banks through the cashpoint or cards.