Chongqing (pop. 16 million or 31 million if you count the built up cities surrounding it)

Chongqing is the largest city on Earth by city area.
The city is built on a mountain, famous for hotpot, spicy food and nature.

Together with the surrounding cities it has a population close to the country of Canada, but many people have not heard of it, which makes it a more authentic Chinese experience.

Apartments are cheap. Teachers pay less than 3000 RMB