After 30+ years of helping addicts I conclude street meth, lab meth, and alcohol are by far the 3 worse and most destructive. Then tobacco and prescription drugs for number of deaths, health problems and social problems. Next the designer drugs like bath salts. Then cracking coca in. ..then heroin.
I know someone in my family who took bath salts. I think if they were around longer, they’d be higher up on your list.