It depends on my needs and wants at the time. I'd want to live somewhere where I can indulge in my hobbies, while still having access to good medical care. I'd definitely avoid developing countries, no matter how cheap they are. I've been an expat for 15 years now, living in both developed and developing countries, and if I were in need of medical services, I'd definitely want to avoid developing countries. People say the medical care in developing countries are top-notch and cheap, but I know firsthand that that there's a reason why the care is so cheap. Even if I choose a top-tier private hospital in the developing country, they may have access to top-tier doctors in their country, but they might not be considered top-tier in a developed country. But perhaps I'm biased, because I have had multiple personal experiences with the "top-tier" medical system in a developing country and can't help but consider the type of care I received compared to what I received while living in a developed country. And over the past 10 years living in a developing country, I have had friends and acquaintances who have had major medical emergencies. Trust me, if you're in a coma after suffering from a brain aneurysm, or if doctors just discovered a Stage 4 brain tumor, you do NOT want to also have to endure the stress of organizing and undergoing a medical evacuation during a 2-month citywide hard lockdown in the midst of a pandemic. You want to already be where the good great doctors are.
There's a saying in real estate that you should buy the worst house in the best neighborhood. I think that concept could apply to selecting a retirement location as well. In the case of retirement, the best "neighborhood" is the best/most expensive/wealthiest country with the best resources, and then go about finding ways to reduce your expenses living in that country.
So for us, we are considering a smaller town with a lower COL adjacent to (within an hour's drive) of a major metropolis in Canada. Stable political system, good educational system, great medical system, clean air, free healthcare, lots of nature. But it's a lot more expensive to live in Canada than say, China, where we are currently living. So in Canada, we will look for ways to minimize major expenses such as housing (by living in a smaller town), transportation, and food.