philly,
Your focus is primarily on music content. I will second the recommendation for the Du Pre Elgar Cello Concerto. A must hear performance. I’d recommend finding a great recording of Holst The Planets also. There’s a Mehta conducted one everyone likes though I’ve not heard it.
For Rock I just can’t go past Jimi Hendrix Band Of Gypsys. Simply because they recorded a genius, live at his peak. Maybe not technically the best guitarist but, for a wholly improvised in the moment, never to be repeated glimpse of his brilliance this one shines. Herbal enhancement is in character for this album. Just don’t become a jellyfish(Band Of Gypsys reference).
For beautiful wordsmithing, delightful acoustic guitar and just right accompaniment Bruce Cockburn Dancing In The Dragon’s Jaws.
There are dozens of excellent female artists. No-one I know has ever expressed anything less than shock at the talent of the late Eva Cassidy. Look for the Live album. One more sublime album Elisabeth Schwarzkopf The Four Last Songs.
I have a soft spot for the Bach Cantatas(along with one for Jimi). One of the first he ever wrote Aus Der Tiefe Rufe Ich Herr Zu Dir. I recommend the one conducted by Hans Thamm.
Jeff Buckley Grace. Santana and McLaughlin Love Devotion Surrender. Phoebe Snow self titled.
Let me not forget to mention the sublime Brian Eno Another Green World and Roxy Music Stranded and King Crimson Discipline. The best Bowie album is Heroes.
There’s a lot of great music.