Bardstown Audio used to have a few pretty good libraries (piano, jazz bass, accordeons). According to the Bardstown website, they're now distributed by Big Fish Audio, but I can't find any trace of them there.
Wizoo — if I remember correctly, the company that sampled the original Halion Strings — had a couple of good-sounding libraries, mainly drums.
And talking about drums: the one library that answers best to the thread's title description is Mixosaurus. In my opinion, still the best sampled drums ever created and unlikely to be equalled any time soon as no current developer seems to see the point in going the amazing distance that Mixosaurus' developer went.
Another excellent drum library that's no longer available is Sampleheadz' Peter Erskine Living Drums. (Some of those samples have ended up, as I understand it, in some IK Multimedia product or other, but the library as a whole has definitely disappeared from availability.)
The very first Miroslav Vitous String Ensembles was quite good too, certainly for its day. (I have the EMU E6400 version, which I later translated for Logic's EXS.) And if used wisely, it still qualifies for a place in a mock-up made today, I find.
Which can also be said of Denny Jaeger's string samples.
The reason I became a member of V.I. Control, 16 or so years ago, was to have it out, en plein publique, with Donnie Christian (who had sold me several libraries but never bothered to send them to me; this was in the days before downloads). Mixed with my extreme annoyance over Donnie's charlatan business practices however, there was always, and still is, a great admiration for his sampling work. Still use many of his woodwinds (despite being very incomplete libraries) frequently, I will never get rid of his percussion samples (many of which sound *exactly* as I want recorded percussion to sound, it's uncanny), and his 'Venus' harp compares favourably with much of what, harp-wise, has been released since as well.
Most of Donnie's percussion samples later found their way, in a cleaned up and remastered version, into Vir2 Elite Percussion, but I always preferred his original release.
And on the subject of wind instruments: Westgate is also still an often visited directory on my sample HD. Something about those samples — woodwinds and horns — that seems to fit my music in ways that few other libraries do.
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