Opiates got me the hardest and made me a slave and I wanted to die by the end of it, by far my worst addiction.
Meth also has a scary pull, I have done it a grand total of 3 times. The first 2 times, the comedown was so bad it made me not want to do it again, but the third time, I had etizolam and just slept. I have had way better highs, honestly... like my first roll was 100x better, I've had tons of psychedelic experiences that I liked far, far better, even something like 4-FA I enjoy more. But for some reason after I did it last time (like 2 years ago) I thought about it non-stop for like 6 months. I dreamed about it, had intense cravings. It was weird and kind of creepy because I didn't even feel like I intellectually wanted it, intellectually there were various other drugs I wanted more but I wasn't struggling with cravings for them. I don't know where to get any and I purposely keep it that way because I know myself better than I did when I got addicted to opiates. I still get random cravings for it.
Also, GHB was super addictive for me.