Well, a while back, I made a lis(z)t of Liszt pieces and my opinion of their relative difficulties:
https://www.pianostreet.com/smf/index.php/topic,3568.0.htmlIts far from being complete, but it contains most of the well known pieces.
that website baohui posted is pretty good, but its also vague..
Leslie Howard plays most everything Liszt wrote for the piano. You can find contents of all 59 discs here:
https://www.hyperion-records.co.uk/details/67414.aspScroll down to the blue links and you have access to see everything. For example, you can find Liszt's transcriptions of Schubert's Winterreise in volumes 32 and 33.
Dover publications has a good collection of Liszt's transcriptions, although it is not complete. Most common opera transcriptions and Schubert Transcriptions are available. I usually buy stuff from dover through Amazon or sheetmusicplus.com. To find the really rare stuff, you may have to contact more authoriative publishers, such as Edito Musica Budapest (
https://www.emb.hu/) or Breitkopf and Hartel (
www.breitkopf.com) and ask if they have it. If the music is really rare, maybe they wont even list it in their website and you will have to contact them.
donjuan