This is, of course, a matter of opinion. I would argue that symbolic interactionism is the most helpful theory in explaining various social problems. However, there are experts in sociology who would pick structuralism or conflict approaches.
Let us take the issue of drug crime as a social problem. I would argue that drug crime is a problem largely because of how we have chosen to define drugs. Many of our problems with drug crimes stem from the fact that we choose to make drugs illegal. If they were legal, they could be regulated and not be put in the hands of criminal gangs.
However, we have at the same time chosen not to make alcohol illegal even though it causes many of the same problems that drugs do. The reason for this seems to be the meaning that we assign to alcohol as opposed to drugs. Since we define alcohol as something that is normal and acceptable whereas drugs are somehow abnormal, we accept the former and criminalize the latter. Symbolic interactionists say that we act toward things based on how we define them. This clearly seems to be the case with regard to the fact that we have a problem with drug crimes.