second tier is real authentic china good and bad

As with anything, there are pros and cons to both. If you like the metropolitian lifestyle, then Tier 1 cities are best. They have lots of foreigners, choices (regarding food and things to buy), and the standard of living will be higher.The cost of living is much more expensive than in Tier 2 cities. Tier 2 cities will have a more authentic feel to them. If you really want to learn Chinese I'd recommend a smaller city as less people will know English. There will still be millions of people and you'll have access to foreign choices, just not all the traffic and chaos of a Tier 1 city.