I believe that drugs are a very big evil, because it not only destroys a person, but the person himself is capable of great evil for the sake of these very drugs. Legalization of these substances gives rise to even more problems.
Legalization is the best option. Because if the drugs are legal, then it makes easier for the law enforcement agencies to monitor the drug users. On the other hand, if the drug business is driven underground, then it becomes impossible to do that.