Re: ASA or US Sailing...who's best...
Not sure of your current experience. As you are planning on taking the basic classes, and not testing out of them, my assumption would be that you are new to sailing. If so, and you are looking at this as a future career, why not take classes from both groups so you can get an idea of the curriculum, testbooks, etc. as well as see how the companies that operate the schools perform. Sailing classes and business research rolled into one. The end result is about the same.
After that you work on your captains licence so that you can teach. That will take some hours of experience, I think over a 100 now, and passing the class. After successfully completing that, and a business plan so the bank will give you money, you will have your chance. Good luck.