Well, after China banned ICOs and exchanges, Japan took its place. I am not sure what country is best for btc buisnesses, but I bet Japan maybe the one. Its pretty hard to answer as countries are different and they all have some pros and cons.
Japan was one of the first super-powers in Bitcoin. Japanese users were using Bitcoin much before the Chinese came in to the picture. You can say that the Chinese were replaced by users from South Korea. That will be more accurate.