I've only experienced butalbital and phenobarbital, so I'm going to say benzos are more euphoric.
For euphoria, if you can legitimately call it euphoria, I like alprazolam. I've had temazepam too, but I still like Xanax / alprazolam better. I'd love to take the alprazolam v. triazolam taste test to see if Halcion is better.
If I ever get to try the good barbs like pentobarbital, secobarbital, and amobarbital, I have a feeling my opinion would switch from benzos to barbs.
I'm saying that because I really liked butalbital the very few times I tried it.
Phenobarbital is odd. I was given Luminal in one of my inpatient detoxes. Back then, I liked it. It made me relaxed, outgoing, and talkative.
When I took it a couple years ago, it was just an extremely heavy, oppressive sedation. I didn't notice any enjoyability.
Although that could have been because I had been taking clonazepam, alprazolam, and diazepam daily for a couple months prior to that.