My intention isn't to insult you; I am interested in what you were playing before these monster pieces? It just seems as though you've skipped a huge step somewhere. If your technique is coming up to those pieces you've listed, consider the musical viewpoint: go back to some easier rep where technique is out the window, and you can just express it in any way you want.
I avoid pieces like Scarbo, Don Juan (for now hehe...) simply because i'll be too fixated on the technical difficulties that it'll sound very muddled if I ever do end up getting the notes down. This is something I realized after spending 2-3 years trying to find 'the most challenging pieces' while I was still in high school.
I worked on some pretty difficult rep (for me) this year, but I decided this summer to go back to some shorter-scale pieces, even the first Arabesque by Debussy, some short Nocturnes by Chopin, just to enjoy myself and not feel like I'm trying to conquer this beast every time I sit at the piano.
I'm telling you, you will enjoy the heck out of this difficult rep if you can get past thinking firstly of the 'challenge' of the rep.
You should play some Beethoven too! Have you played any of his Sonatas? You should look at Op. 13, Op. 78, Op. 90, and maybe even one of the late ones... they all have 'challenging' moments, but there is so much expressive writing in these pieces that I think would be a vital complement to some Liszt (transcriptions, etudes, mephisto waltz, etc...). I am not saying that Liszt isn't expressive, but people tend to gravitate towards his pieces as would a budding guitarist to the sweet (and crazy fast) solo in a song rather than just playing the whole damn thing.
Again, I don't mean to insult you, but if you do a quick search, there are TONS of posts like this one where people just ask for the hardest piece to play. Inevitably, Sorabji is mentioned, and the thread closes
So yes, I hope you take a look at the suggestions I'm giving you, and make use of the search on the forum. I've been here since 2004, and there is an absurd amount of detailed information on pretty much all of the piano repertoire floating in the archives here. I will still arbitrarily search a piece (for example: Liszt 'Funerailles'), and see the amount of threads that mention it, that feature it, recordings people have made, etc. Look for some rep that interests you (and challenge yourself to pick a slow piece! You need to give your fingers a break haha), and just read up on it. It's really enlightening seeing what other forum members experience working on this very same rep.
Topic: Next Piece to Play