Which is better - choosing With or Without Conversion at ATM in Sint Maarten?
You'll want to choose Without Conversion for sure. It's the best practice everywhere you travel. The ATM in Sint Maarten will offer you a convenient conversion from Netherlands Antillean Guilders (ANG) to your home currency, but it's a terrible rate. Your own bank's exchange rate, even with a small foreign transaction fee, will almost always be better.
It's a no-brainer-always choose Without Conversion. The local banks in Sint Maarten, like Republic Bank, are trying to make a little extra cash with Dynamic Currency Conversion (DCC). You will get a much better rate if you let your home bank, for example, your Revolut or Wise card, handle the conversion. Don't get fooled by the convenience of seeing the price in your own currency.
Without a doubt, go Without Conversion. I was in Philipsburg last year and the ATMs at the bank branches all gave me the option. I chose to let my home bank do the conversion, and when I checked my statement later, I was happy I did. The exchange rate was much better than what the ATM was offering. It's a key tip for anyone traveling with a non-US-dollar card.
You should always choose Without Conversion at the ATM. It's the most reliable way to get a good exchange rate. When a bank like The Windward Islands Bank (WIB) ATM offers to process your transaction in your home currency, it's a trap. They make money on a poor exchange rate. By declining and letting your own bank do the conversion, you're more likely to get the official market rate and save money in the long run.