I'm gonna havta go with weed cause you cant overdose (well if you did you'd be a smoker legend) and the more you smoke the higher you get. Alcohol is great up to a point before it goes from stimulant to downer, and blackouts, headaches, and hangovers suck.
I'll take either depending on which is more easily available and whether I want to go crazy or relax myself. Beer is always good. Sure spirits are great and all, but nothing beats a good cold beer.