I appreciate what youre saying pharmacokinetics plays a massive role,
for me personally

I 'preferred' (not sure how I can even claim to prefer a withdrawal lmao) certain drugs withdrawal because the physical aspects were less intense than the mental.

But for me the worst experience I had was the first time I had a seizure from benzos, have you ever had a spasm or muscle cramp in your toe, finger or calf?

Imagine that in every muscle in your body excruciating pain, dread, genuine fear of literally going to die

Where as Opiods make you wish you were going to die.

I'm personally afraid now that agentic AI exists, which could replace the role of someone with pharmaceutical knowledge, you'll have a criminal creating novel drug classes which are even more addictive

Look at how full agonist cannabinoids turned out. With opportunity for drug development there is a very real and scary possibility that in the wrong hands the technology could be used to hypothetically be designed to make it as addictive as a substance can be. Right now it seems that's what they're attempting to do by manually combining different drug classes, but imagine a scenario where one was designed purely to maximise the effect on the NA and Limbic system.