This is really a question for you guys, out of my own curiosity.
I personally prefer psilocybin sex. I am not as experienced with shrooms as I'd like to be, but on my strongest trip I was convinced I was an Aztec goddess and that my then-boyfriend was a sun god. It made for some pretty interesting fucking. On acid, my newfound Buddha-consciousness tends to distract me from what is happening around me, and I only periodically remember that I'm getting fucked. Not really worth it.
How about you? Which do you prefer? How are they different?