Central banks are usually owned by the country they operate in. If the would start selling shares to the public and try to become a public company, that would be nice. Personally I would definitely invest in a central bank. Their funding comes from the government and their loans to commercial banks are usually backed by the government as well. It's a pretty solid business model with a lot of government guarantees. A great way to make money for the owners.
A decentralized Bank cannot belong to any country, it can belong only to its co-owners and is managed by all owners. The platform allows all ETHEREUM holders, when connected to it, not only to save their assets, but also to multiply them.