Liszt's Second Ballade is a massive, storm-tossed work of epic proportions that pushes the limits of Romantic piano technique. Its frequent use of chromaticism and expansive structural shifts define it as a masterpiece of late Romanticism.
The greatest technical difficulty lies in executing the rapid, cascading arpeggio passages and powerful, sustained chordal climaxes.
Comparable difficulty and character — good candidates for what to learn next.
Ballade No.1 is rated Henle level 8 of 9 — concert repertoire, roughly diploma level. In the RCM system it corresponds to about level 10.
You should be comfortable at Henle level 8 — meaning you can already play level 7–8 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 Ballade No.1 lasts about 15 minutes.
Ballade No.1 is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Ballade aus Der fliegende Holländer, Wagner by Franz Liszt, Bénédiction et serment, 2 motifs de Benvenuto Cellini de Hector Berlioz by Franz Liszt, Ballade aus Wagner's Der fliegende Holländer by Franz Liszt — see the full similar-pieces list on this page.