3. Shenzhen 

Population: 13.03 million

Area: 2,050 square kilometers

Transforming from a rural village to one of the world's biggest metropolises in just three decades, the fast-developing vibrant city Shenzhen has become a firm favorite for migrants. 

Designated as one of four special economic zones in 1980, Shenzhen has expanded at a rapid pace. It now has the third largest economy in China, attracting international investment because of its special tax benefits and preferential treatment.

The city's population increased by 498,300 in 2018 – the largest growth of any city in China. Migrants are enticed by its favorable talent policies including expedited residency rights, increased minimum wage and housing discounts.