I would try Shenzhen for the 320. I would say that they have had their act together better than any other 320 operator in China as far as hiring expats for the last couple of years. It can change tomorrow.
This statement will probably make no sense to someone who never worked in China. If the office that handles the recruitment of expats doesn't know what they are doing, they will screw up most of the recruiting. And it will cost you your potential job, through no fault of your own.
This permeates every facet of your job in China, from the food you eat, to your medical, training etc.