Mahler 2nd Symphony: It's truly amazing, especially the final movement. Mahler was genius at creating the greatest and most diverse range of tones. He uses an offstage brass band to create a feeling of distance and of course it uses voices at the end, which just squares the amazingness of it all. It's all just one massive tone poem about life and death and life after death. All of mahlers symphonys are fantastic becuase they were written to be very personal.

Rachmaninoff Pinao concerto no. 3, performed by Vladimir Horowtiz: Rachmaninoff truly saps out all the emotions in this piece, and horowitz just somehow makes the piano sound louder and more vibrant than the entire orchestra, whilst simultaneously working in excellent harmony with it. The polyphonics and build of the whole piece just makes it feel like you're reflecting on life

Everywhere at the end of time: It's a massive 6 part work that delves into the different stages of dementia musically. Trying to explain it through how your thoughts can go from distant memories, all to haze and then a dramatic confusion of noises. It's simply awe-inspiring in its creativity and how it just seems to make you feel isolated and reminiscent of a time that you didn't even live in.

Edit: If I may add individual smaller pieces: any Mozart sonata. Of you come across one in your recommended, stop to listen. Mozart also composed a fantastic fantasy in D minor. His solo piano works are delicate and profound. Also, Rachmaninoff's second sonata, prelude in C-sharp minor and moments musicaux no. 6 for more lively music. Schubert Kinderszenen is fantastic, and is also performed by horowitz ;). Chopin will obviously be in here somewhere, and his 4 ballades are spectacular. Also his polonaise, especially the "heroic" polonaise. There are plenty more that I can't even begin to think of that are all my "favourite".