Not that I've planned it for that reason, but my family has the documents to live in either Japan or Switzerland. Both seem reasonable bets to me, i.e. protected by geography and with a pretty resilient local population.

Have a read on the Bronze age collapse - when the global economy collapses, the main danger won't be environmental but due to human migration. In a functioning economy I'm very liberally minded towards freedom of movement (and in fact this lessens the danger I'm describing), but in a collapse, global inequality will come back to haunt the developed world in an apocalyptic fashion.