Alcohol is really just a total waste of time in my book, but, I have been known to drink a few beers now and again just to be social.
Tobacco is an awful, inefficient, highly addictive drug that everyone knows kills. So... I'm trying to quit (I'm down to about 1 a day!

).
I will not do coke anymore. The come down is really bad, and there is never enough. My nose and sinuses end up just fucked for about a week, and even hours after its worn off I can't sleep. And I'm here in SoCal where its everywhere, most of it is good, and its cheaper than most other places in the USA... still won't touch it.
DXM was fun the first few times but I really just don't like dissociatives. I've also never found it as a powder, and drinking cough syrrup (even if its just a bottle of Zicam Cough Max which is only about 1.5oz by volume) is just nasty.... *shudder*
Never done meth, and don't really plan to... but a LITTLE Adderall every now and again is nice.
Hydrocodone isn't really that much fun, but I like oxycodone, codeine, and morphine every once in a while. Methadone is the worst opioid I have ever come across.
Piperazines are EVIL.
SSRI/SNRI/Antidepressants are a mixed bag. I've gone on stints of Lexapro, Welbutrin, Paxil, Proac and Effexor. They all helped a little bit (each in their own way) but they all had MASSIVELY BAD SIDE EFFECTS. I haven't taken anything along the lines of these in many years...
Nitrous Oxide is only worth it if you are under the influence of a psychedelic (such as LSD) AND if you don't do it too much or too often causing a vitamin deficiency.
I've only done K once but it really fucked up my nose (not as bad as coke though) and wasn't much fun (see earlier comment about dissociatives). I wouldn't seek it out, but if it found me I might be willing to give it another go.
I don't like psyclocybin mushrooms, they just give me too much body load. All I want to do is lay on the floor and watch the ceiling shift and swirl while I'm nauseas... for hours... LSD is amazing though!
Kratom is a waste of money just like most legal highs.
Salvia was just plain uncomfortable and confusing.