I think it is a situational thing. Years ago I heard various rumors of a full bladder improving your performance and/or intensifying orgasms, so naturally I had to try it. There are times when I've waited until I couldn't hold it any longer, then masturbated. There was a certain rush and intensity to the orgasm, followed of course by the bliss of emptying a full bladder.
Other times the results were - "Glad that's over with, so I can go piss"! When it comes to intercourse, the full bladder is usually more a hindrance than a benefit.
With that said, I try to make sure I don't urinate just before sex because I like to be able to go pee after an orgasm to flush out the plumbing. Otherwise I seem to have annoying seepage of some remaining semen several minutes later - when it is inconvenient and/or messy.
If I were with a partner who was into watersports, having a full bladder for sex would probably have a completely different perspective.
Of course most men can relate to the good ol' morning piss hard-on. I used to sneak out of bed to go to the bathroom so I could stroke it. More often than not, by the time I reached the bathroom - the urge to piss overrode the urge to jack off.
Now, since my wife and I have opened up sexually, I give my morning wood plenty of attention each morning before I finally get out of bed. A few minutes of edging - stroking my hard on through the soft velour blanket - then drift off to sleep - wake up - edge - sleep - this can happen several times before the alarm clock goes off. For whatever reason, I don't feel compelled to finish off with ejaculation. i'm happy to get out of bed and go relieve my bladder - most times, that is - sometimes I have to take it all the way 😃
Overall though, I think the best part of orgasming with a full bladder is the pissing afterward.