Hi all,
From my experience doing medicals and having issues for the last few years in both CAAC North (Beijing) and CAAC South (Guangzhou). CSA/CAAC South is by far easier and more practical. (for China).
Regarding the companies you listed, I am not familiar with the 747 contract possibilities, however.
I remember talking to Uni Top guys a while back and the issue they had was, while they were waiting for training, permits, etc, they were only paid a low basic salary because their contract was based on a low basic and then had huge allowances and bonuses. I personally would prefer to take the company with a high basic salary because while you are grounded for any reason before and during the contract, this is normally paid. You might be promised $20,000 flying allowance, but if you are not flying, even through no fault of your own, you get ZERO.
Good Luck