My favourite is probably the rare fourth one but really they are all really nice.They are also quite easy (it seems): I have never actually learnt them but from looking at the scores they are basic. Yet they have such a powerful effect despite the easy writing.I wouldn't say that the fourth is easy though: see here to get the rare sheet music:-https://www.gamingforce.com/forums/attachments/musicians-library/411-classical-sheet-music-liszt-valse-oubliee-no-4.pdf?d=1141554355If you are interested in a recording of Leslie Howard playing it, let me know. I have a lot of the Leslie Howard Liszt CDs.