It need to be a country that is safe for foreigners, low crime rate, clean environment, clean air and water, decent level of health care, good food. Poorer developing countries often does not fill all of these requirements. A few does.
Which countries are those?
Thailand, Dubai, UAE, Belize, Cayman Islands is suitable countries with 0% tax on trading.
Then there is a bunch of countries with low tax on trading income, in Czech Republic it is 15%, in Sweden there exist a special insurance account type that are taxed at ~1% year for total amount.