1: Shrooms. The best trips of my life have consistantly come from shrooms.
2: Opium. It's nice and mellow. If I were to become addicted to anything, it'd probably be opium. So I try to stay away from it, barring special occasions.
3: Weed.
4: Mescaline. I've only taken it once, but it was the longest trip I've ever had. I took it at 6:30 p.m., it didn't kick in until 11 p.m. and lasted until 2 p.m. the next day. I walked around, feeling like I personally knew everyone at the concert I was at, and lemme tell you guys, that is NOT a good way to conduct yourself in public. My friends also told me I kept trying to eat the lights as they washed over us.
5: Acid (sorta maybe). I took a hit of this stuff at a party, and funny stuff happened, but I'm fairly certain it wasn't acid. I remember lying in bed, with my eyes closed, and my body pretty much moving nonstop. Like my hips wouldn't stop shaking, or my leg wouldn't stop kicking. Also, my mind was racing like never before. Later, I found a guitar and played the best version of "Four Sticks" that I've ever heard.
6: Alcohol. Bottom of the list because anything more then a shot of whiskey kills my stomach. Ever since I downed a bottle of absinthe for my 21th birthday, my stomach has pretty much been fucked when it comes to beer.