I love Japan, I really do but they speak almost 0 English and their language is really hard to get good at.

Also taxes in Japan seem to be quite high, on par with the Netherlands.

Baltic states look interesting! According to google Estonia has a fixed 20% income tax.

Although I'm not sure how to pick between them, all three look kind of similar. I've also surprisingly never heard about someone migrating there for financial purposes. I've always thought of the US as the only place to make a lot of money.