Though its different with everyone, all of you have valid points, however, if you are going to use a mind altering substance, weed is the best all around choice period.
Lets not forget its appetite stimulating qualities, and its amazing ability to reduce stress, which we all know tears down muscle and inhibits gains...
weed benefits:
stress reduction (a biggie for bodybuilders)
appetite stimulant
vascularity enhancement (studies prove this, fellas)
aids in good rest/sleep
provides an outlet that is not high in calories and carbs (beer)