DXM. Technically it is a dissociative, with some additional mechanisms like serotonin norepinephrine reuptake inhibition and sigma agonism.
In lower-ish doses, they are very dependent on your liver enzymes and can range between maybe as low as 75mg and as high as 200+mg, it is an euphoric stimulant (so-called Plateau 1. Look out for W. Whites DXM FAQ on Erowid) and diminishes cravings for opioids. Even helps with acute withdrawal if you take enough but not too much..
Took it daily for months in my youth and somehow was a time of my life. Certainly better than opioids but unfortunately Ive ruined it by using the shit out of other dissociatives, leading to long lasting tolerance. Its own addictive qualities shouldnt be under estimated but guess who already kicked opioids will manage it with DXM. It's not for everybody but worth a try.