1. Estonia
2. Lithunia
3. Latvia
4. Switzerland
5. Japan
6. South Korea
7. Malta
8. Singapore
9. Germany
10. Philippines
That's currently the list on my mind, obviously not in particular order though. And I'm sure those countries are far more advance that others because they know that significant effect of being a friendly crypto nation.
Why those countries in that list? When you say friendly, do you mean the country government is open to implement crypto based companies or because the population is involved in crypto?
Those countries on the list are doing something to adopt crypto currency payment system and also supporting crypto exchanges with regulations so they also can get benefits from it.