Methadone: Methadone is a weird opioid in my oppinion, in that it is VERY potent, but the ammount I've always needed to get high has always been wayyyy larger than what is necessairy to keep me comfortable and out of withdrawals. The high, is very similar to heroin IMO, possibly more so than any other opioid I have tried, but it's a lot more sedating which I personally find to be annoying. Furthermore, tolerance builds insanely fast to methadone which is also a pain in the ass. I've kind of come to the conclusion that this drug is really best just for maintenance or detox. Getting high off of it is too difficult and dangerous, and the tolerance buildup is a real bitch.
Hydrocodone:There has literally only been one time in my life that I've had access to hydro, as well as a low enough tolerance to make taking it worthwhile at the same time, that being said, that one experience was really nice. I'll probably get shit for this, but if hydrocodone was more potent, I would prefer it to oxy. The buzz is very warm and stimulating, and it lasts a long time. I also found, strangely enough, that even when taken orally, hydrocodone sort of has a rush. Of course it takes a while to kick in, but it seems once it does, I feel like it peaks rather quickly.
Oxycodone: I'm one of the few idiots who's first opiate was heroin, and in fact, I had never seen an OxyContin pill until I had already been shooting dope for three years, and even to this day-I've only messed around with OxyContin or Oxy IR about 5 times. Oxy is a good opiate, but I personally feel that it's a little bit overhyped. As an IV drug user, I found both OxyContin and roxicodone huge dissapointments, as there is no rush whatsoever to speak of when injected. I'll just get that dope taste and then be immediately high. The actual buzz though, is very nice and stimulating, I just feel like its way to expensive of a drug for what it delivers.
Oxymorphone: When my friend hooked me up with the 10mg Opana IR's for the first time two years ago, I felt like I had been blown by an angel. Oxymorphone is probably my favorite opioid. The rush is better than heroin, the buzz is similar (but more euphoric) to oxycodone, and it is potent as fuck. I never thought it would be possible for an injected opioid to feel better than heroin, but IMO, oxymorphone is most definately superior. I also really like the high as well, it's pretty damn long lasting (even when injected), and like hydrocodone and oxycodone, it's a stimulating but a simultaneously calming experience. A fuckin' plus.
Heroin:The first opiate I tried. Heroin has it all as far as I'm concerned. The rush is incredible, the high even better. People talk of MDMA as being a very empathetic drug, but IMO, heroin is much more so. The high just makes me feel so comfortable and compassionate towards myself and others. I can litterally be in a room with my most hated enemy, and if I'm on smack, I'll find something beautiful about the individual. Dope also gives a more "natural" feeling high IMO, compared to the pharmaceuticals. It's definately more sedating than the Thebaine derivatives, but I still get a nice energy from it as long as I measure out my shots well. Heroin also gives me some very strange audio and sometimes even visual hallucinations if I'm nodding out. Sometimes I'll find myself talking to ghosts, but it's never a frightening experience, just another little oddity that I actually enjoy.
Buprenorphine:Buprenorphine as a recreational opioid is limited, in a similar way as methadone is. It's incredibly potent and has a long half life, meaning tolerance builds up fast as hell. However, if you aren't tolerant or addicted physically to strong opiates, buprenorphine can provide a very nice high, one that is better than methadone IMO. It feels a lot like hydrocodone or oxy to me, but even a little more stimulating. Due to the long half life, a suboxone high can be felt the next day, which is pretty awsome-even methadone could never do that for me. When injected, the rush is nothing to write home about, but the effects seem a bit cleaner-however, I've found plugging to be almost identicle in onset, but the duration is longer. As a maintenance drug, I also love bupe, because at a low dosage, I am consistantly able to get a nice high from it up, two times a day (I take half a milligram in the morning, and another half in the evening, sublingually). On a low maintenance dosage, suboxone/subutex acts even more as a stimulant to me, which is especially helpful, as there is no maintenance drugs for speed or cocaine.
Fentanyl: I've only tried fentanyl about five times, but I honestly do not like this drug, potent or not-that does not necessarily make it better. IME, fentanyl feels more like a VERY strong benzodiazepine rather than an opioid. The high is incredibly short lived, and the euphoria is pretty lame compared to oxycodone, oxymorphone or heroin. There is just something very cold about this narcotic, and it's way to sedating for my taste.
I've done other opiates/opioids as well but the rest of them have pretty much just sucked, so I don't want to waste time writing about them (I'm thinking about codeine, propoxyphene, and tramadol).