Prepaid travel cards are fine when they work, but some terminals can decline them for seemingly no reason as other members of my party to the USA found out!
I've travelled to the USA and Spain in the past couple of years, for the USA I had a Chase UK debit card (with free cash withdrawals at any Chase ATM), and a Monzo debit card. Where the Monzo card didn't work, the Chase card did, and really I could have got away with just the Chase card.
For the Spain trip I set up a Santander bank account, they allow fee-free cash withdrawals from Santander cash points (but do charge for transactions, so it was purely going to be if I needed more euros), and I took my Monzo card, and Barclaycard Rewards card. The Barclaycard sat in the hotel safe as my Monzo card worked everywhere flawlessly (incl contactless). The Chase card was MIA shortly before the trip or I'd have taken that as a spare instead of the Barclaycard.
An important tip to remember in Spain, they must charge you in EUR or you'll pay an eyewatering conversion rate, a couple of small shops insisted I paid in GBP because it was a British card...
No transaction fees and Visa/Mastercard currency conversion rate for the Monzo, Barclaycard and Chase account. Monzo is great as it will ping your phone for every single transaction whether successful or declined.