Alcohol. Yes, it will turn you into an asshole at times and make some of your mornings suck. But, it generally tastes good and allows you to communicate with the shitheap that is most of humanity without crying.
Pot. Like being paranoid and hungry? Love cartoons? Have a job/spouse that doesn't care if you are super lazy, then this harmless drug is the one to go to.
Shrooms. Four hours of seeing the world from a different perspective. Colors! Sounds! Downside is that Phish and Prog Rock will suddenly make sense and do you really want to be that person?
LSD. Shrooms with lots of shitty chemicals and it lasts far longer than shrooms and you'll really wish it was done before it is done.
Cocaine. Will make you feel like a god and will get you laid - but not with anyone you'd ever really want to get laid with. If you are a girl get ready to be sucking the dick of some sketchball you may call a "boyfriend" simply because he has access to coke. If you are a dude get ready to go broke. Will certainly eventually turn you into a complete asshole either way.
Heroin. Make sure your grandma has a nice television and you know where the local pawnshop is before you try it. Also, buy burglars tools in advance.
Meth. No teeth, psychotic rage, live in squalor. Male or female you'll find yourself sucking dick for it (which is easier once your teeth fall out.)
Ecstasy. God, do you really, really want to like techno? And to need to walk around with a pacifier in your mouth so you don't grind your teeth? Plus, smart drug dealers mix heroin into it now to get you hooked on a brand new drug!