I was a Xanax addict for 9 years and have done almost every single drug you can name.
Opiates - Feels like you're wrapped in a nice warm blanket, floating on a cloud, and nothing bothers you. The comedowns are harsh and make you really irritable. Very easy to fall into addiction from how good it feels.
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Benzos - Makes you feel like you are unstoppable. Nobody is better than you, you have no fears or anxiety. You will act like a COMPLETE asshole and not realize it. You feel very tired, and there's little to no actual "high" but rather a feeling of no worries.
I VERY MUCH hate this class of drugs. Xanax literally RUINED my life.
Since benzos lower your inhibitions (ability to make good decisions/control yourself) it is very likely you will re-dose thinking "Ah man, I feel it but not enough." then once you re-dose it's a vicious cycle of "a little more won't hurt" then you end up taking the whole bottle and it turns you into a huge asshole walking around looking drunk as fuck.
You lose chunks of entire weeks/months/years worth of memory, PERMANENTLY. If you do manage to get clean, you will have a hard time putting together eloquent sentences or thinking on the fly. It DESTROYS your brain.
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LSD - I actually like LSD a lot. It opens your mind and you think completely different than you ever have before.
It's like you turn into a philosopher just sitting there pondering for 12 hours while staring at moving walls and colors floating in the air.
A bad trip is all about your mindset. If you start thinking about sad things, your trip will go bad. You don't actually hallucinate people like media makes it out to be. A bad trip is simply your mind wandering into bad places and feeling the emotion 10x stronger than you would sober.
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MDMA - You will feel very hyper and happy. Things will feel very nice to the touch, smells will be more noticeable, and you'll have a numbness all over your body. You grind your jaw a lot too. All senses are enhanced and the comedown is pure hell. It's like your anxiety intensifies 10x. It's fun but not worth the comedown in my opinion.
I was bored and typed this all out. If anyone wants to ask me about a drug I didn't list I can tell you about it, I'm sure I tried it at some point.