What is the most powerful stimulant known to man?

Well, from a doctors point of view it would have to be meth. Meth because it is the only drug that mixes "uppers" and "downers". So after taking meth for the first time you might feel withdraws when coming down from your "high". When the upper and downer mix it is a high that no other drug offers. When you come down your body has withdraws because it wants to feel "so good" again. Now not only is that a very good reason why it could be the most powerful stimulant. But, after doing it for a while it just tears your whole life apart. You start to loose weight at a drastic pace and that is not good. Your teeth and hair may fall out. And you Itch all over.