Luanda is the most expensive city in the world for an expatriate professional migrant to live in as at July 2017, followed by Hong Kong and Singapore. The top ten most expensive cities in the world comprise one from Africa (Luanda (1)), three from Asia-Pacific (Hong Kong (2); Singapore (3); Tokyo (7)), four from Europe (Zurich (4); Geneva (5); Oslo(8); Monaco (10)), and two from America (Hamilton (6); Manhattan NY (9)).

Luanda in Angola is the most expensive city in the world for expatriate professional migrants to live. As opposed to Hong Kong, everything in Luanda is expensive as almost all international standard goods and services are imported. Despite the lower oil price, the slow-down in oil related projects, and dramatic reduction in revenue to Angola in 2016, prices in Luanda remain extremely high.
https://www.xpatulator.com/cost-of-living-article/International-City-Cost-of-Living-for-Expatriate-Professional-Migrants_716.cfm