Definitively ccards, especially, as mentioned above, contactless is king. And this is true everywhere, urban or rural.
Note, however, two things (1) American Express is not widely accepted here, nor in many parts of Europe for that matter. Despite their claims in their commercials, it's more a "local" card to the US than anything else and most businesses elsewhere do not accept this card. And (2), in the very recent past -I'm talking a 4-5 years ago- some cards issued in the US, especially by smaller banks/coops, were not up-to-standard to European security measures (Pin&Chip, etc...) and sometimes visitors from the US had problems using them here. I believe this is now no longer the case as it's supposed to be a standard in the US too, but double-check with your bank.
As per mobile payments (ApplePay and the lot), in Spain is not really 'a thing' as it doesn't provide any further benefit over existing payment methods (ie contactless). Yet, ApplePay, for example, which if I am not mistaken is issued by Goldman Sachs Bank and is on the Mastercard network, can be used anywhere Mastercard is accepted as the terminals are compatible with contactless. But again, I'm not 100% sure, maybe someone else can shed more light on this.
For info, all taxis (at least in Catalonia) do accept ccards.