From what one of my friends told me, there are over 50,000 training schools in China which have at least some classes that are foreign language ones. The overly excessive negative posts you see on this board has been compiled over time. People don't just plan 5 years ahead to systematically come to the board and slander so many schools. The problems of ESL teaching in China have been well documented and if you're not careful you will be suckered in the traps and pitfalls that many if not all of us on this board have been through. However you can be assured that if the bigger schools have a bad reputation, then the smaller schools generally will be even less reliable to work at being they don't have as many resources to make themselves look legitimate. Freshly graduated college students in China are even starting private training centers.

The cities you have listed are all reasonably good places except for perhaps Hefei (the air there isn't very good and many parts of the city are still being built). However being that the ESL market in China except perhaps out west and near Vietnam have already been developed for over a decade now you'll find a vast array of places which means there will be crappy schools in even the best looking, expat friendly cities (like Suzhou). Also you realize that many of the posters on this board have a lot of experience working in China so just asking a general question like this isn't really going to necessarily elicit good responses.