I am from the Netherlands and I recently went to Switzerland. When withdrawing Swiss Francs from an ATM I got the option in which currency I wanted to charge the money on my account, Francs or Euros. I am wondering whether any of the two options is cheaper, better or smarter in some way and whether this depends on the current exchange rate of Francs-Euros?
It depends on the (retail) rate/fees your bank/credit card company is charging compared to the rate offered by the bank/money changer operating the ATM. Both depend on the current exchange rate but they are not identical to the interbank exchange rates.
Your bank should provide information on fees and exchange rates (for example here are the rules for ABN-AMRO), while the rate offered by the ATM operator is usually displayed at some point before completing the transaction on the machine itself.
I always go for “charging in local currency” and let my bank do the change. I vaguely remember reading somewhere that it's usually better and at least I know what the fees are and I avoid huge rip-offs. Beyond that, I don't actually know if it's always the smartest or cheapest solution.