Psychologically addictive? First would be cannabis, because I love it so much, then would be Dexedrine. I plugged 7.5mg just once when I was already on a non-recreational oral dose a few years ago, and the instant onset of effects, mildly rushy euphoria, and increased BA scared me away from using that ROA for d-amphetamine. It gave too quick and too intense of a recreational effect, that I soon after took a benzo and went to bed try to counteract the potentially addictive high.
I was just using my dexedrine prescription for ADD purposes, I didn't want to get high on amp and, subsequently, to get addicted to chasing that high. That being said, I was curious and somewhat stupid to plug it while using it for that purpose, I just didn't want to take it orally it on an a full stomach since it was late already, and sublingual amp ruins teeth enamel.
I'm sure if I ever tried/got high on coke, meth, heroin, or GBL, my answer and life might have been drastically different.