The most common question I get from clients is what type of bankruptcy I think they should file. In some cases there is a clear benefit from one type of case over the other. In many cases both of them will be just fine.
It is possible that someone could want a chapter 7 bankruptcy and not be able to qualify for it. Sometimes people make too much money or they cannot do a chapter 7 because they have a prior chapter 7 within the last 8 years. It is also possible that you could want a chapter 13 bankruptcy and not be able to qualify for it. Sometimes there is no money available to make the minimal monthly payment needed to fund a case.