I believe that a nod is not necessarily euphoric, depending on the person. I know people that love oxycodone but won't touch morphine if you paid them, while others are the opposite. I think the nod is the most subjective euphoria of the opioid/opiate experience. With that being said;
From a perspective that focuses strictly on euphoria it would have to be either oral Fentanyl or insulffated (snorted) Demerol. Smoking the Fentanyl would also give you euphoria but it would be a much different euphoria than that of oral Fentanyl (think of really good crack compared with really good lines..it's euphoric but it's different). My personal favorite if its for euphoria would be oral Fentanyl b/c when you smoke it you definatley get more sedated as opposed to more euphoric, the more you smoke.
Demerol is euphoric simply because it's not really a true opioid, since it affects many, many receptors the main ones being the opioid, the antichlornigenic (sp) receptors that belladona affects, as well it hits the seratonin and dopamine receptors. Thus when taken insuflated in doses of 75mg-100mg you get a feeling that can be described as a rough draft of the fentanyl euphoria with a huge twist (but a good twist) to it. You can't nod out on doses under 75mg insulfated so you are stuck in this haze where you can't really nod out but you can't stay awake either. The experience feels like you would have 1-2 lines of really clean coke, along with a good/relatively solid dose of hydromorphone or something a bit synthetic like oxycodone, topped off with a dose of Benadryl that's *just* enough to make you sleepy and see small visuals (50mg-75mg).
My own personal favorite, and in my subjective opinoin it would have to be morphine insulfated (snorted), b/c it has the euphoria and a true stony high that I love. I don't really like the synthetic or semi synthetic opioids b/c they're too upbeat and you can't really catch a nod unless you focus on it or try but with morphine its hard not to catch a nod, even when your standing up. After morphine it would have to be either pure codeine sulfate/phosphate or hydrocodone, I could honestly care less. I would have pure codeine pills over oxycodone pills anytime of the week for the same price or more even just because I like the stony, mellow high. The third favorite would have to be methadone which if you don't take daily (neither narcotics) you can get very high and euphoric from it in a stony way like morphine. The reason I put it 3rd is because I find the others more euphoric.
BTW, Hydrocodone is extremily rare in Canada where I live, and I have been looking around for years! I believe that Vicodin is more available in the States than it is in Canada. Where I live the streets are flooded with Dialudids and Oxys, and Morphine isn't very hard to find either but I have never seen Hydrocodone other than once when my dad had it for cough and another time when a family friend got it also for coughs (in syrup form). What do you think Canadian blue and green lighters am I right on hydrocodones' availability in Canada? Demerol is rare as well but I have definatley been able to find it on occasions, but so is fentanyl...these things come on occasion and only if you know the right people or right places.