So over the years of doing drugs I have come to find that I don't like the man made ones nearly as much as the natural ones. I am not saying all synthetic drugs are bad, but the rule seems to be that the closer they are to natural ones the better they feel. For example, hydrocodone is semi synthetic but it feels pretty good and natural although not as good as heroin/morphine.
Now compare that with suboxone, i just cant enjoy it. Not because of tolerance, I can get high off of suboxone just fine as my tolerance is relaly low. Fentynal also, But the high just feels icky to me. It doesn't feel right. Same thing with , fentanyl, ketamine and benzos, they just dont feel right compared with natural herbs like kava and valerian.
Another example of a good synthetic drug like LSD, its actually really close in structure and effect to natural drugs.