The Swiss banks are the best if you don't mind AEOI.
AEOI is only between OECD members or they also share with other countries?
What offshore jurisdictions do swiss banks accept?
A country doesn't need to be an OECB member to participate in the AEOI program. There are maybe 20-30 countries in OECB but AEOI has thousands. Also a country doesn't need to sign the AEOI agreement to exchange information with other countries. They can always use other means: on request or spontaneously.
I don't think all countries have interest in sharing information.