Ativan (lorazepam)...I don't find benzos euphoric really (not on their own at least), but this one kills panic attacks and puts me at ease so quickly and pleasantly.
I dislike both klonopin and particularly xanax (which I find very choppy and disorienting). Valium I don't mind, but it seems less effective for me than then the others, less potent (which it is, technically).
Other benzos (temazepam, oxazepam, nitrazepam, etc) I've tried just make me sleepy (haven't tried any of the rarer, supposedly good ones, mind you).
I have a 2 mg vial of midazolam in my drawer that I'm itching to try but I have to get my IV skills back up and running first.