I know there are at least a few high-quality albums which, due to their age, were only printed on vinyl or cassette, but never to CD.

I don't own a turntable or a cassette player, which makes these impossible to listen to.  However, it is possible to make a digital transfer from vinyl (called a needledrop) - which I'm planning to do for good albums which were never printed digitally.

That being the case: are there any non-digital releases you'd particularly recommend?  The only one I know about (which I already have a copy of) is this one:

07FA-1106    Hikari Shinwa: Palutena no Kagami / Metroid Original Soundtrack Orchestra Version

Looking back at history, VGM really came into it's own (in Japan) after CD's had begun entering the mainstream (in the mid to late 80's). So there really aren't a lot of vinyl-only releases, if any. Even the one you have listed, there is a cassette version (I know because I've been outbid on it before!)

The vinyl dilemma mostly comes into play for a lot of non-VGM stuff prior to 1986-1987 when releases were not large enough to warrant a CD release, as vinyl was still dominant at the time. When CD's got big, they worked on pressing the big stuff to CD (Beatles, Zeppelin, Van Halen, etc) and a lot of stuff was left as vinyl-only. VGM largely escaped that part of history.

If an album was printed to cassette, it's still something I'm interested in, as long as it was never printed digitally.  I've made that more explicit in my OP.