Cover versions of songs can reveal the "quality" versus "flimsiness" of the songs themselves, especially covers that take the song into new territory. You know that already from some well-known classic songs - even in rock and pop where lots of well-known stuff might be a great song or might just be a great delivery. My surprise with Radiohead was that, even for the tracks that are most solidly "rock", when other people cover Radiohead -- as reggae or 8-bit or whatever -- the strength of the songwriting shows itself: Radiohead's tendency to inject an interesting "something" into the chord structure of many of their songs, for example, provides the kernel that allows the song to remain distinctive even when people try to transform it. I'm interested to find out from that which Bjork tracks have "good bones".
My prior expectation is that a lot of Bjork's music rests on her vocal adventures as well as her adventures in techno production, neither of which carry over into cover versions. But then, on the other hand, I did previously think Radiohead's "Kid A" was all about wallowing in production effects, and I wasn't right about that! - They have some actual tunes buried in there, which the cover versions brought out.
The way to tell a good Bjork cover version, or a Bjork song that is good enough to be covered well, is when you're listening to the other artist and not hearing the echo of Bjork's voice throughout. There are plenty of covers that fail this test, which can be either because the covering artist didn't try/succeed to make the track their own, or perhaps because the track doesn't support it.
Hence, after some detailed inspection, here's a pretty small list of cover versions that pass the test! They're all great:
And an honourable mention for the classical string group "Wooden Elephant" for their instrumental cover of the whole album "Homogenic". -- In one sense it's not what I'm looking for, especially as Bjork already focusses a lot on strings in her production. But when listening to this performance, I noticed that they've done one thing very successfully: they've integrated to vocal melodies in with the other melodies, and they haven't tried to make it sound like a human voice, but just another string voice in the very nice diverse string orchestrations they come up with. So... well, something of an aside, really, especially since this is a slightly avant-garde classical performance, not exactly the pop cover version.
...
OK, so what? Where has that brought us? I rejected a lot of others: one thing I notice is that for many singers it's quite hard to get away from the Bjork vocal quirks that they remember from the original - they're often tempted to reproduce them, at least a little bit. That's something of a trap because it draws them away from putting their own stamp on it. The versions I've listed here are the few singers that really get away from that and fully make it their own.
What do we learn about the music? Well, that's not up to me. This selection spans lots of years/albums, but only from the range 1993-2001 (then again, that's also the most well-known material). Some of the covers do reveal some new strengths in the composition that I hadn't seen before. Will people be covering some of these songs twenty years from now?