I'm using Roamless because the eSim is pretty cool, automatically swaps to whatever country I'm in, rates are near local prices, and the best part is it's pay as you go and your balance doesn't expire. There's plenty of other good services too, but they charge for a certain period of time while still being limited data. Some are unlimited which are pretty cool though, but haven't seen another service that's able to swap between countries like Roamless though.