All things equal, I would agree that the CELTA certificate is the most desirable as—unlike the others—it is administered by a single accrediting body: Cambridge. It is the only certificate to have for those who are thinking about teaching in Europe. However, if you were to successfully complete the intensive
7-week summer TESOL program at Columbia University, I don’t think any prospective employer in status-conscious China would think of it as a second-class alternative.
The more important issue, I think, centers around the overall importance of any EFL teaching certificate for the purpose of facilitating the speaking and listening skills of students in China. I would say the vast majority of Chinese employers realize that given the severe limitations of the foreigner’s role in their de-professionalized EFL program, degrees, certificates, and even prior teaching experience are unnecessary. One's innate ability to charm and entertain Chinese students, and to remain flexible and open at all times with the saint-like patience of Job are not predicted by the possession of a CELTA, TEFL, or TESOL certificate.
In reality, a college degree is far more important for obtaining university EFL employment in China than possessing an EFL teaching credential (TEFL, TESOL, CELTA) and the hiring advantage is negligible I think.
As an employer of foreign teachers in China, I’m sure Ken will want to weigh in on this as well.