I politely disagree Turnoi. Aston, EF, Shane and other similar schools have the best online marketing presence, and most rigorous recruitment campaigns, thus will attract a lot of qualified teachers who want to teach in small, intensive environments. It doesn't mean that such teachers couldn't find a job elsewhere, but merely that they didn't, in the beginning, have any reason to suspect that these schools wouldn't treat teachers well once they came to China. Also, some of those schools are OK, if they are in cities where a boss doesn't believe he's their master.

The private school has many advantages over teaching in public schools when it comes to actual teaching English in the classroom. One has small class sizes, good books and workbooks to work with, AC, and students are places in a wide range of levels based on their speaking ability. If private schools treated teachers well, they could be ideal places to work at. However, being private businesses, they typically exploit teachers in every possible way to maximize short term profit (and at the expense of long term profit).

Public schools are better in terms of work load, benefits, dignity (you don't have to have English Corners in McDonalds), and in almost all regards, except that they usually have very large classes with students of mixed ability, poor texts, and no AC.

I currently work for a university and it's a much better life than when I worked for private schools. However, I'm a much better teacher for having worked in private schools. I've had to teach all levels of students and every aspect of grammar in the most interesting and engaging ways I could come up with. At the university, one only really needs to walk in the class and hold conversations or debates, and read over the material in the texts. People teach with no TEFL and no real world teaching experience, and consequently their classes are boring, and the students mostly don't even talk. Only the best students will engage in conversation while the others drift off.

I've also met lots of teachers from different schools, and it's pretty clear that the teachers at private language schools are the ones who actually have to do the real teaching that one wouldn't know how to do if one didn't do a proper TEFL or CELTA Of course private schools get bad teachers who can't teach and just fake it, and that's what they deserve, but, for good teachers they provide an environment where they will have to really teach.

Thus, I wouldn't write off teachers who'd had the misfortune of working with unscrupulous schools. In fact, I'd prefer teachers who've had to test their metal in demanding teaching environments rather than teachers who only needed to coast along in public schools where teaching was more just going through the motions because, well, how can you teach 40 or 70 or 90 students at a time effectively?