Spain vs. Portugal (Lisbon)

Hola todos,
I am living in the US now and, after retiring early, am interested in moving to Spain or Portugal. I traveled to Spain last Fall and also have been to Portugal a few years ago. I am wanting to get a retirement visa to one of those countries and was wondering if anyone on here has been through the process. Also, are income taxes about the same for Portugal as Spain for non-EU citizens?
I will be using retirement income to live. Thanks!
Mike