The US taxes citizens on world wide income, no matter where they are resident, so they are probably the worst choice among the first world nations for the super rich. There are people, like Eduardo Saverin, who give up their US citizenship to avoid US taxes.
The UK is a haven for a lot of these people, as it has a very attractive non-domiciled rule (live in the UK, only get taxed on UK income or income which you bring into the UK - income which stays out of country is effectively untaxed).
Or, perhaps a jurisdiction like Hong Kong with no capital gains tax might make sense.
I think there is a reason why Chinese money heads to West Coast USA / Canada and Russian money heads to UK. The large Asian population in the Coastal North American cities makes it a place that a rich Chinese person would actually want to live long term and send his family there. It is a place where they would have an easier time assimilating.
The UK is a haven for a lot of these people, as it has a very attractive non-domiciled rule (live in the UK, only get taxed on UK income or income which you bring into the UK - income which stays out of country is effectively untaxed).
Or, perhaps a jurisdiction like Hong Kong with no capital gains tax might make sense.