I prefer LSD; but I'm definatly not saying its a better psychedelic. They both definatly have their charm, but LSD just fits my personality better.
I prefer the longer duration; I like my trips to last long so I can enjoy it longer. The duration of LSD, which for me is usually around 12 hours, is just about perfect for me. Another huge preference is the type of visuals; I like the fact LSD visuals are brighter, fractalish, more neon, múch more detailed patterns and with more parts of actual images in it, like faces or cats or tiny black 2D people. Mushrooms visuals are a little more pastel, blurry and shiny, which I also like, but I find the ones on LSD better. Then there's the mental effects, I like how LSD is clear, fast, active and awake with a high stream of very associative colourful surreal thoughts, while shrooms are generally very confusing, although mentally also very interesting. Then the bodyload makes it easiest; mushrooms make me feel weak and cold, while LSD is a bit of a stimulant making me feel just right.
Don't get me wrong, even though I prefer the more complicated detailed visuals, clearer mind, longer duration and less bodyload of LSD; I also really like psilocin; its a great psychedelic and it has so much potential for the seriously deep stuff; I like them both a lot but I prefer LSD on almost every thing I can judge it on.