Pot. Currently I have quit for professional reasons. Piss test reasons.
I believe in moderation, will power, strength of character and intellegence to dicipline yourself into the knowledge of what your level of moderation is. Some drug's you simply cannot moderate and should not get near. Pot however is not one of those drug's that you can`t moderate...and with a simple toke which can last you 4 hours of being high, you can easily quit this drug with no physical side effects or physical addiction.
Mental addiction is a different matter. Marijuana does have advantages that the media will not talk about that can become a crutch to some. Existential thought, increased motivation, increased energy and creativity are hightened to levels not normally ascertained (for many...depending on the individual of coarse, some become relaxed and/or tired). These effects are both useful and entertaining. These same constant hightened functions are sought after by some who believe the effects dissipate if the marijuanna use is stopped. However, I find that the contrary is true...once you quit the benifits you have recieved can strengthened your character, where as too much use can hinder your growth as a person. Problems arise when the drug is used too much, but it is my understanding that too much of anything is a negative. Paranoia, due to social phobea`s is an example of pot`s negatives...but you all have heard how pot can hinder.
Heh, and the people that do get addicted to pot...well, they are weak willed. (I don`t respect weak willed people) They are usually the type that smoke tabacoo, and have tried quitting smoking 10 times. These people typically will not even attempt to quit pot, and will smoke everyday...and far too much. A weekend toke never hurt anybody that I can even fathum...in fact, some of the most creative minds of our time have taken the odd toke from time to time. George Carlin, Bill Mahr and John Lennon are three that come to mind.
Personally, I do not believe in legalizing pot, not until the idea of moderation vs abstinantce is properly integrated into society...however, I do believe in decriminalization.
So there is your answer.
Edit: btw, the only other illicit drug that is agreed on to have no physical addiction is LSD, but I dont know this for sure.