Since my tastes in classical music tends to be on the atonal, and "thorny" sounding side, musically speaking, YMMV.
But sonically, these are worthy.
LP:
Ernst Krenek - Static and Ecstatic (1972)
Amazing for demonstrating image and soundstage. This thing creates such a 3d soundstage, it is easy for me to imagine I can get off my listening seat, and walk into the soundstage and steal a bow from a violinist. Dynamics are also very good.

Charles Wuorinen and Donald Martino
Again, great 3d soundstage. Good dynamics, very detailed. And again, "thorny" sounding music.
Back in the 70's, the budget label Nonesuch, did a series of recordings called "Spectrum: New American Music", that tended all to be recorded very well.
Several years back, I was at an audio event here in LA, where Peter McGrath (recording engineer with Wilson Audio) gave a talk. Afterwards, I approached him to discuss these recordings, not thinking he would know about them. As soon as I mentioned them, his eyes list up. Turned out one of his mentors engineered a bunch of these. He made a statement something like, "considering how good these budget recordings are, it is a real indictment on modern recordings".

CD:
Augusta Read Thomas - EOS: Goddess of the Dawn (2015)
This is on the consistently good, Reference Recordings label. Huge, layered soundstage, dynamics to spare, very coherent. Percussion is particularly well recorded.
Musically, this is on the more "approachable" side of my tastes. Definitely modern, but not a super challenging listen.
Jason Serinus, in a review for Stereophile called it a "sonic spectacular".
https://www.stereophile.com/content/sonic-spectacular-utah
I recently discovered the Kairos Music label
https://www.kairos-music.com/, that is loaded with the type of classical music I love. So far I have bought about 10 recordings of theirs, and so far, they have all been recorded very well.