That's an extremely subjective question.
Absolutely.
<EDIT: I realised that I kind of went off-topic here as I assume OP was asking about RCs. I'll leave the post here anyway, in case it fosters discussion. Sorry OP!>
Also, I think the word 'euphoria' is used pretty loosely when people are talking about substance effects. While it generally means 'feeling good' or 'a sense of wellbeing', there tends to be booster words in most definitions (e.g. an
intense feeling of wellbeing, or
great happiness). I think most substances feel 'pretty nice' rather than intensely amazing. And while intense happiness can appear here and there with substance use, it tends to be fleeting and/or mixed in with lots of other feelings.
Generally speaking though (in terms of 'feeling pretty good'), I find alcohol can produce some euphoria, even though it's often combined with other, shitty feelings (irritation, anger, excessive sentimentality) and can leave you feeling like utter garbage with a hangover. If only indulged on rare occasions, a nice scotch whisky can be worth the hangover, in my opinion.
3-me0-pee cee pee was sometimes genuinely euphoric, in my experiences. Em Ex E, as well. I miss them both a lot.
Smoked/vaped stims can do the job in terms of a burst of euphoria (m3th, a-PVP, cr@ck), but as with alcohol, there's often an inversion of those feel-good effects later when the crash hits. I wouldn't touch any of those without a boatload of benzoz to hand these days.
Personally, I'd have to say 0pia+es are the best for feelings of Zen calm, for kicking back and feeling like all's right in the world. 0xy can be fantastic. H can be awesome. If I could have an unlimited supply of any of them, I'd choose good ol' natural 0pium - it's strong, has super long legs, and is pretty non-toxic on the whole.