Definitely heroin. You want a few long tips spikes for when you first start cause youre gonna be jabbing yourself trying to find a vein and those little ones are just useless...
Oh and meth too, thats always good. Lmao
In all seriousness if you wanna fuck with something, smoke some weed then try some mushrooms or DMT.
Changa/DMT is wild and in my experience not addicting whatsoever. Pretty fucking intense if you do enough of it. Read up on it, shit is wild.