shiner
Lifer
From a technical perspective, Paul is the better vocalist. He was a choir boy, and the training shows.
John, meanwhile, like many great artists, does not have a technically great voice, but he has the raw emotion that will convey drama and impact. He might not make it into a choir, but he can sell a million albums. An extreme case of this type of performer would be the vocalist for Dire Straights - that guy cannot even sing (he talks all the songs) but there is something in his voice that makes it a great performance nonetheless.
If you want to talk "best voice from a trained and technical perspective," the winner would probably be Celine Dion. She won a boat load of international vocal competitions even before she became famous. I'd put Brad Delp of Boston up there too. Most people cannot sing the songs he did. Try a Boston song on Karaoke sometime. 🙂
You should be banned for mentioning Celine Dion in a Beatles thread.