This may come as a surprise to anyone who remembers me (the guy with nearly 100 B minor Masses), but there's a lot of Bach, including some major pieces, that I simply don't know or don't know well. I've recently begun addressing this.
I had music books in the 70s and tried to teach myself the inventions but they were pretty hard for a teenaged rockhead, though I did manage to learn a couple. I bought my first Bach recording around 1986 or so. I think I have one recording of the WTC (Book I presumably) that I never listen to and couldn't tell you whose. Schiff on the inventions, also rarely listened to. I thought I had all the solo violin works, but it's just one CD so maybe just the partitias, and also couldn't tell you who the performer was. (I live in one city, work in another where I have a small apartment so I can't check.) Never had any recordings of the Goldberg variations or solo cello works. Don't think I have the English or French suites, though I may have one of them on a disc that I bought for something else. You can probably see I'm not a huge fan of solo keyboard works or chamber music in general--nothing against them, but I'm just more likely to reach for something bigger. (Have always loved the violin and harpsichord sonatas though.)
But as I said, I've started exploring these famous but largely unknown-to-me works. I bought Gould's WTC1 last week, then last night made a sizable purchase of Ashkanazy's complete WTC (so yes, only on piano, but I'm not stopping there), Kremer's solo violin sonatas and partitias, Koopman's organ works, sonatas with viola da gamba and harpsichord, Schiff's Goldbergs and Viersen's solo cello suites. Choices were made largely based on what the store had.
Enjoying this journey through the undiscovered territory of a composer I know so well though his sacred music.