I spent a good year trying to develop a website to answer this question and collect responses from people who'd done just this to try to aggregate their qualitative and quantitative experiences, before ultimately realizing this is something where you can sort of point out some of the obvious trade-offs but the value system and preferences of the individuals vary so much that unfortunately the only way to really determine it is for the person in question to go live there. And so I stopped working on the site and just got a one way ticket and spent a year remote working.
Before realizing that for me at that stage in my life the best place for me ironically was the country where I started, just in a bigger city with a good metro system.
If you wanna determine this you'd be best off constructing a matrix of priority systems (weather, cost of living, language, broad cultural region a la northern european, southern european/latin, east asian, latin american, etc), nature in the area, etc) and make a tool for an individual to rank their priorities in terms of categories/factors, then rank the options _within_ each of those categories/factors, and then try to score the results for them. But even then, people often don't know what they want or care about until they've experienced a variety of places.