Great post bro,
2nd and 3rd third tier cities are where it's at. A good balance in everything.
I lived in 1st and 4th tier.

1st tier cities have the most pollution. Lots of car honking, loud vendors yelling out sales and construction noise is inescapable. The working environment can be competitive and stressful even though the pay grade in those cities are attractive.

4th tier cities, It's pretty boring in fourth tier. Fewer sources of entertainment than higher tiers. Hard to get by without speaking Chinese, unless you have a translator with you all the time.