The purpose of a stop bath is to quickly and completely stop the development process. It makes development predictable. A weak acid solution, like 2 percent acetic acid, does that admirably well. But I have always used a simple water rinse - usually a quick rise followed by a second rinse of about 30 seconds. It works fine, and I'm used to doing things that way. But a simple water rinse may not be all that certain for everyone.