Quality is in the ear of the listener. Although I like both songs and recordings, I like the Jimmy Mack song much more, and would pay more than double for it, were rarity not a factor, and fate would determine that I could only ever possess one of the two. Of course, given that I am a general Soul music fan, as opposed to an NS fan, and don't just limit its value to that on the NS scene, and melody and singing skill, and natural gift of voice count more for me than the song's beat and the resultant abilities to dance to it, my preference probably doesn't count much in terms of your quality criteria.
And maybe the original "perception" among collectors, that the Jimmy Mack was the rarer issue, and a large find of several boxes of it many years later, with them not disseminated all at once, caused the information that there are now more of it known to not have been absorbed (realised) by most collectors. I, myself, had seen People's Choice a few times back in the late 60s, years before I knew Jimmy Mack even existed, and at first it was thought to be super rare. And that difference (impression) had been in my mind until your comment in this thread, which triggered in my mind, the more recent memory, that, "yes, come to think of it, I have seen more of The Macks around lately."