Since I love lists of music, I will be happy to offer up some pieces of music that just slay me with their pathos, sublimity and ecstasy. There are many pieces that I can choose, but these are perennial favorites. Once you find the right recording of each, then it stays with you forever.
1. II. Largo ma non tanto from Johann Sebastian Bach's Concerto in D minor for two violins, BWV 1043. Of course, this selection has been bowling people over for a long time, but for me it hit home completely with the harmonia mundi France performance of Andrew Manze and Rachel Podger with the Academy of Ancient Music. They completely get what this music is saying. They start out pretty reserved in their telling of its story, but the music and their filigree gets much more impassioned as the movement progresses. This is music of the sublime.
2. III. Adagio from Wolfgang Mozart's Serenade in B-flat major, K.361 "Gran Partita." I will admit outright that this music was delivered to my soul by the movie Amadeus. I saw this movie when I was in my infancy of classical music. The way the character Salieri described this movement, and his admiration for it, was the way I needed music to be described to me. Something that sounds mundane (What's more mundane than reed instruments?) but in the instruments' conversations with each other, so much more was being created. It is completely what Mozart is about. He may never reach heavenly heights like Bach, but he can sure mimic it from his earthly station.
3. III. A Convalescent's Holy Song of Thanksgiving to the Deity, in the Lydian Mode from Beethoven's String Quartet in A minor, Op.132. I heard this piece live in Ames, IA performed by no less a quartet than the Emerson when I was rather young. It hit me like a ton of bricks. It is so supplicating, so contrite and thankful, and to have that come through music alone is astounding. Beethoven was a gruff man, but he must have had conversations with the deities, because he knew how to write music that speaks directly to the soul. Nothing beats this movement in all of classical music. I tried to have my older sister walk down the aisle at her wedding to his music. She went with Pachelbel, of course.
4. Pas de Deux from Tchaikovsky's ballet, The Nutcracker. This is beauty of another type. It activates the emotions-on-one's-sleeve part of me that just wants gorgeous sound to wash over me sometimes. It is what music filled with pathos is supposed to sound like. Tchaikovsky was good at that for sure. It isn't a nuanced portrait of sorrow, it is raw and unyielding, like the sixth symphony. It comes from pain and so is completely honest.
5. Section 1 of John Tavener's The Protecting Veil for cello and orchestra. I heard this on the radio when it first came out. I had no idea it was part of a larger work, and frankly, I don't need it to be. The combination of a plaintive cello line with the warm hues of strings alone that supply such strong consonant harmonies makes me feel a tremendous repose. Given that this piece is part of the mysticism school of music, I think it achieves its aim. It really conveys that sense of responding to the grand questions of creation and religious mystery.
As I made the list, I realized that the selections I chose are the best examples of music by those composers. They are a reflection of that composer's true self. Bach, surrounded by God, writes heavenly music almost without exception. Mozart's music is warm and sincere when he wants it to be, and there are times when it is just a paycheck. But the Partita is not one of those pieces. Beethoven was a man of grand conceptions, world unity, universal love. His music speaks to that and the string quartet movement in particular shows his truest self - difficult on the outside, a lover of mankind on the inside. Tchaikovsky lived a hard life of want and shame. Music that speaks to that part of himself, or his attempts to work at that, are usually his best pieces. The Nutcracker was written for his family's enjoyment and comes from a place of devotion to those who loved him, and so is completely sincere. The Pas de Deux is just one aspect of that. John Tavener is a devout Catholic and that comes through many of his compositions. Although some may doubt the staying power of his mystical compositions, no one can doubt his earnestness in creating this work for cello and orchestra. God, I love what classical music can invoke in us, without words even. That would be a separate list.