Well it depends on what you mean by productive. I'm a musician/artist. So cocaine makes me real productive and efficient in my likes. But then what drug am I most productive off of. That'd be heroin. Boy the things you can write and create while craving.
I take ritalin for my sleep disorder which helps me with attentiveness in class and such. But musically I can come up with some pretty mad licks and lyrics after a bowl or 2
I'd have to say a really good sativa weed. Nothing too stoney but a soaring cerebral high gets me going. Sometimes a few bumps of coke help. There have even been points in my life where I depended on opiates so much that I would actually get energy from taking them. Weird.
ABSOLUTELY NONE haha i dont want to do shit but listen to music and usually dance when anything besides bud is goin on
Coke I would say DXM because of the crazy things that go on in my head and all the ideas I get (I write a lot), but I'm usually too messed up to do anything with them.