The Spanish farms would be a good vacation spot, but continental Europe isn't a place I'd base my operations.
Belize is a good choice. English as its official language, it's reasonably close to America, low population density, friendly terms with the UK, a small but UK-trained military, long guns are restricted and pistols require a permit (but can be obtained easily with some cash).
Costa Rica would be nicer, but prices higher. Firearm laws in CR are much friendlier, but fairly restricted for non-citizens or permanent residents. OTOH, there's tons of private security companies and it's not hard to set one up. From the sound of it, you could buy some property, set up a corporation for that property (say, APS Resort LLC), set up a security company (APS Resort Security Inc), give a local national a 51% stake in APS-RS Inc and get normal firearms at inflated prices but without having to bribe anyone. Costa Rica healthcare is as good or better than the US on average, no anti-vaccination movement. They do have a national carry permit, again, only for citizens or permanent residents.