Before you can make much progress on your quest, you're going to have to answer a number of questions for yourself.
- Do you like warm weather or cold? Seasons or a constant climate?
- Are you willing to learn a new language?
- Is your current nationality one that makes you a desirable immigration candidate?
- Are you moving for retirement, or to work?
- Do you want a radically new cultural experience, or something pretty similar to where you came from?
- Do you need modern luxury or would you be happy in a developing country?
- Aer you bringing a family or moving on your own?
Without knowing the answer to these, it's hard to give you very good advice, because different countries are better for different people.
Though I will admit that cathinfrance's answer (France) does cover a lot of ground - a range of climates, and different levels of development, urbanization, and cosmopolitanness (cosmopolitaneity?).