I think the Street Drugs are way cooler, because you got nice stuff like MD or some trippy shit, which can help you to get into some nice adventures. Also Party Drugs are only street drugs, so if you want to have fun with your friends all night long the doctor's office is not for you.
And medical Drugs, thats only ugly shit - I mean nearly all medical drugs are only that tranquilizer / painkiller / narcotics and this is only for boring people lying around in their flat and not moving anymore, thinking this is a kind of cool feeling ... i don't know ... more for people with anxiety disorder or who don't tend to be in a mentally prepared status to go on psychedelic journeys.
Plus: Medical Drugs and especially those painkillers are like 95% addiction causing, so even though they come from clear sources, its more the thing for filthy street junkies - not so for MD or LSD.