As soon as you find out that “One,” apparently, came from Harry Nilsson getting a busy signal on a phone one day, that can dominate the way that you hear the song, with the repeated keyboard note dominating everything else around it, including the harpsichord and strings (and flute, I think? From 1:32, that is) that carry the weight of the song outside of Nilsson’s voice. Deetdeet deetdeet, deetdeet deetdeet, and so on.
By the time that Three Dog Night have their collective hands on the song, it’s already lost the fragility of the original version; the vocals have gone from Nilsson’s softness to the overblown rock wail of Danny Hutton, and the carefully built structure of the original is replaced by something that aims to rock you but feels scattered and as if the band has forgotten how the song actually goes, and are trying to hide it with harmony vocals (“Num-Burr!” indeed); this arrangement feels curiously at odds with the lyrical content of the song, but this was also the version that was the bigger hit, so I guess that the late ’60s kids were more willing to accept aggression from a moustachioed rockhero than melancholy from a soon-to-be carwreck.
I’m tempted to say that Aimee Mann’s version of the song – from the soundtrack of Magnola – is the one that I prefer, in a lot of ways; there’s the sadness of the Nilsson original, but also a stronger dynamic than that one, with a structure that makes more sense than the Three Dog Night version – adding in the organ and bass, as well as Jon Brion’s backing vocals (The section at 2:10 with, apparently new lyrics and melody, is just lovely), brings something to the song that feels more in tune with what the song is actually about, instead of the overblown theatrics of the Three Dog Night version.
Ultimately, I prefer the Nilsson vocals from the original, but I find myself wishing that he’d had the thought to add what Mann/Brion did in their version for some weird Voltron final version. But then, what song doesn’t have some missed opportunities down the line?