Unless you are going to attend an actual in person program, there is not a lot of difference between the major certification programs. ACSM was excellent years ago, requiring in person testing with practical application included. But even they have moved away from that format. There are some very good schools scattered across the states, but there are also some very bad ones. As far as Hong Kong, I wouldn’t be able to help you beyond that. The important thing is that you take it seriously and spend time learning after you get certified. Never teach an exercise that you haven’t done yourself and evaluated for potential problems and value for the client you are working with at the time. If an exercise seems unsafe or if you don’t have a reason to have the client do it, don’t use it.