Your choice is great. None of those cities have made as much progress as fast as Beijing has made compared to how things used to be there just 20 years ago. Even western media had to admit how drastic the difference in air quality is nowadays and how much of a success story Beijing has been in terms of cleaning up the environment. Even the water is so much cleaner nowadays and there are countless parks and green spaces. You can literally see it: https://english.beijing.gov.cn/specials/livablegreenbeijing/index.html

It’s one of the most liveable cities in the world now. I know a lot of westerners are infatuated with the more flashy, hyper-modern cities in China like Shanghai, Shenzhen, Guangzhou, Chongqing, and so on, but for me the urban planning in Beijing is just on another level.