Originally Posted by
The Chemist
If you want a 20m+ city that's one of the safest cities anywhere, excellent public transit, good street food, good cycling infrastructure, and a relatively low cost of living (as long as you're not looking to buy an apartment) Shanghai would be an excellent choice.
I've looked at multiple Chinese cities and have tried to force my way in as a prof, as I haven't had much success, which leaves Mexico City an interesting option.