The Rostopovich suggestion reminds me to suggest Bach's solo cello suites by Pierre Fournier on DG in addition, if you can find it. (419 361-2).
For Bach's solo violin sonatas/partitas, those by Milstein, Szeryng, and Grumiaux are all outstanding in their own ways.
All of the above are old recordings, but fairly good sounding re-releases. If shear musicality is your interest, rather than recording technology and historically informed performance standards, you simply can't do better than these old guys. Late night listening, for sure.
Oh, and let me cast my dissenting vote in favor of Glenn Gould's 1981 rendition of the Goldberg Variations, which over the years I have grown to much prefer compared to the famous 1955 recording. But no need to quibble: get them BOTH (and more) on the 3 disc "State of Wonder" release from Sony.
Beautiful Gould quote in the wonderful liner notes: "The purpose of art is not the release of a momentary ejection of adrenaline but rather the gradual, lifelong construction of a state of wonder and serenity." Amen. Certainly explains his preference for Bach!