I always look at these type of lists with a skeptical eye. There are many factors with expat living that make a list like this useless without factoring personal tolerances and flexibility (or lack of).
For most of us I think the best first decision is to first ask:
1. What are you seeking really by planning to retire overseas? If it is perceived lower costs, remember that may be true only if you ( and your spouse) are willing to accept much higher convenience costs.
2. If it is for the experience and adventure - good for you! However I suggest you start with identifying a continent of preference and reviewing the common issues there before being overly concerned about a specific country on a list. For example, if central Europe how will your U.S. Dollar retirement fare in Euro-land? If South America or Asia, how patient are you with inefficiencies?
3. Don't underestimate the importance of knowing the local language. If someone tells you it is not required, don't buy it unless you want to live in somewhat isolation and forgo much of the richness of the people and culture.
4. Travel and rent first always, several month minimum in any place you are seriously considering. Use the time to seriously evaluate your personal aggravation factor, experiences with local food shopping, medical, and true security issues (on security do not believe what you read, it can easily be much better or worse than outward appearances!)
5. If either of you have any somewhat serious medical needs, don't go. Medical care is really better in the States than the majority of places in the world, including Europe or the UK.
Remember that there is a big difference between those expats living overseas for work, and those retired. The former (in fair disclosure I am one of these) have a built-in support structure, the latter do not. Big difference. Don't be discouraged, just careful!