My gut wants to say LSD, in which i've experienced what i feel to be the pinnacle of human experience. That peak in the trip when all questions are answered, and my mind is in perfect harmony with my body. I am able to fully control myself for the first time. It's paradoxical to the state of confusion and disarray that is often associated with psychedelics.
I've always preferred to identify myself as a musician, and i've had trips that allow what is 'truly' inside to fully emerge. I've had multiple instances in which a symphony would just flow through me, without thinking about it. During these miraculous moments my voice would sound perfectly in tune, more crisp and defined than it ever had before. My breathing was deep and rich, the guitar seemed to play songs itself through my hands, songs that i have never even heard or thought of before. And the songs would just melt into each other. It would be like musical telepathy. This only happened on perfectly timed trips with zero distractions. Like fully accessing the singular bank of human thought and creativity, the same way any virtuoso could do on a regular basis. I could walk away from this experience with a sense of fulfillment, knowing what i may be capable of in the perfect scenario.
I like how JackARoe compares feeling physically good to emotionally centered. And for me, while speedballs and even just heroin are incredible physical highs, they can't touch the euphoria provided by the fully immersive and emotionally balanced tuning in of the mind and body that we sometimes experience with the more 'enlightening' drugs.