Weed. MDMA. Coke. Shrooms. DMT. Alcohol.
MDMA and Shrooms are my favourite. Probably because they are the most mind bending and the effects are prolonged. Don't mind the severe comedown on MDMA as long as I have weed, chocolate and tunes. Mushies have no comedown. I just have a really nice sleep and feel awesome when I wake up. Coke is good but it just gives you the same confidence as alcohol but with more control over your own body. Conversations are pretty cool on it. Comedown isn't too bad for me. Probably because I've never done enough. Weed serves a purpose but I'm an on/off pot head and it's not a great lifestyle to lead when you're on it unless you can discipline yourself to moderate the habit. Same with every drug I suppose. Although, with some drugs you can take then not want to do them for a while like MDMA (mainly for serotonin replenishment). Those are the best kind imo. Alcohol is pretty cool but I think the comedown (or "hangover" as it's better known) is the worst of them all if you have too much.
Want to try Valium, Morphine, Mescaline and Acid. I think Iboga and Ayuhuasca would be a step too far. Maybe one day...
edit: Oh yeah, got spiked with Ket once too. That wasn't great. I've heard the best way to do it is by only having one key. Otherwise you're at risk of k-holing.