For myself external prostate massage with a finger/vibrator, works better than internal does with a finger/toy. YMMV.
When I've done it myself/had it done it just made me leak more precum and externally it felt great but I don't like internal anal stimulation/sex and I'd rather be spanked, whipped, flogged, paddled, and have a crop used on me than have receptive anal sex.
Some men do not get pleasure from an internal prostate massage or receptive anal sex.
Also lots of men can't cum hands free from internal prostate stimulation only and many will have to jack off in order to.