Eurochick
The difference in cost between Halifax Clarity or other cost free options and the most expensive ones, that charge a 3% conversion charge plus fees isn't negligible at all, it can be well over 5% in total, so a few tens of pounds per holiday, so it can be like getting an extra meal during each holiday for free, compared with using a card that charges.
I stupidly lost my Halifax card on day 1 of a holiday in Mallorca so we had to use another card and I worked out that it cost between £20 and £30 extra in fees due to the more expensive card.
We now have a Santander Zero card as well as the Halifax Clarity and at least one of these cards has a different number on DPs card, so if one is lost and has to be cancelled, the other will still work.
As far as credit limits go, Halifax have always been a bit mean to me, and it's currently £1k, and they keep putting it down to £500 (I have a perfect credit rating, everything is paid back on DD, but I'm one of those who exploits all the loopholes to make money out of the banks) but the Santander Zero card has a £5k+ limit, so more than we would ever need, hopefully, but our current account is with them.
You just have to watch for (and reject) any 'helpful' offers to pay in pounds, because the exchange rate is dreadful (worse I've seen is over 10% in cash machines in hotels). Always pay in the local currency.
Also watch for cash machines that charge - they seem to be appearing in Spain this year, don't know about anywhere else. Bank machines seem to be OK (and plentiful - even small mountain villages nearly always have banks and cash machines) but those outside Spar or in hotels seem to have started charging.