J.S. Bach's '3 Choral Preludes' are organ works, often transcribed for piano, which present a chorale melody in elaborated or ornamented form. They are masterpieces of Baroque counterpoint and expressive harmony.
The primary challenge lies in clearly delineating the cantus firmus while maintaining independent contrapuntal lines.
3 Choral Preludes is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 7.
You should be comfortable at Henle level 6 — meaning you can already play level 5–6 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of 3 Choral Preludes lasts about 3 minutes.
3 Choral Preludes is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.