On a per capita adjusted basis UAE/Dubai blows about every other place out the water for number of incoming rich migration (even on absolute basis they are near top). Much easier to get an investor visa, far lower taxes on business income, you can easily import servants and trade duties are miniscule. Everything is available if you are rich because all you must do is fill out some relatively simple paperwork and whoever you want appears.
It looks like in this age for the rich the optimum is something closer to dictator capitalism, as democracies start to embrace more regulation and social redistribution schemes. Singapore and Dubai have been winning choices so long as the people in power don't change their mind and start splitting skulls.