Any standard four-week program leading to a TEFL certificate seems to be fine in China and throughout the rest of Asia. If you were trying to teach in Europe, then anecdotal evidence suggests that the CELTA is better. Unfortunately, this is no authoritative accrediting body for TEFL (although Cambridge in England is the accrediting body for CELTA and DELTA) so, basically, you have to choose based on the criteria that I mentioned, as well as total cost and convenience (see chapter on TEFL Training
The truth is, you don’t really need a TEFL certificate (or a degree for that matter) to teach oral English in China. Having just written that, you will probably find it to be vocationally useful if you’ve never taught EFL before, and it might make you a little bit more competitive for your first teaching position. Certainly, you will find a job a private English language school without TEFL certification and I think most universities would consider you as well. In fact, if you find yourself teaching in a major city, especially at a university, then you could always attend such a program during the summer or winter breaks.
If you have any other questions, please feel free to ask.