There is nothing visibly superior per se about Paul’s moustache; they all were pretty much rocking the Brawny towel guy/ borderline pornstache look, but for some reason I am physically attracted to Paul so much more whilst her had his ‘stache. I don't really know why -- maybe its because the 'stache (as I will continue to refer to it as) gave him that immediate "I'm-not-a-fucking-choirboy-so-stop-saying-I-look-like-one" air and he became instantly more mature and less innocent-looking. Also, he became visibly more badass during this time -- taking LSD, wearing really great 'hip' (I suppose one would say...) suits, rocking paisley and whatnot.
Alas, as the story goes, all good things must come to an end -- Paul was the first to shave off his moustache after the Sgt. Pepper publicity finished, whereas John kept his for a few more months, Ringo and George keeping their for a few more years. When Paul re-grew his during the mid-70s Wings years, it just wasn't the same. Perhaps it was because the moment had passed and the stars were no longer aligned or some malarkey like that, or perhaps it was because in addition to a moustache, Paul also had a mullet.
Yes, I think that's why it didn't work as well.
I think you know what I mean: