Hard to say, hard to say... Depends on my mood. Do I want severe emotional crisis? Schindler's List Theme will do, or perhaps the Romeo and Juliet Theme performed by Andre Rieu (kills me). Or maybe even "Into the West" or "The Black Gate Opens" (the part with the pan flute is so heart-wrenching)
Do I want to just stir up my emotions? Then basically the entire Hunchback of Notre Dame soundtrack will do, but particularly "God Help the Outcasts" and "Sanctuary." Others that will do are "The White Tree" (LOTR: ROTK) or "The Battle of Pelennor Fields" or "The Bridge of Khazad-Dum." I swear, there was a time where I listened to that like ten times every single day...
If we're going the classical route, I'd have to say one of my favorites is the Variations on a Theme of Paganini Rachmaninoff piano concerto, the full 20 minutes will do. Or Totentanz, by Franz Liszt (also a piano concerto - I love those the most. My favorite form of music, I'd say) Ooh, I almost for Tzigane by Ravel (violin concerto)! And of course, we cannot forget Ballade no. 1 in G minor by our (or mine, at least) favorite Chopin!! Woot!
Now, finally, if you're talking like, actual SONGS, then I'd say.. Um...
Coldplay: Death and All His Friends, Amsterdam, A Rush of Blood to the Head, Clocks, basically all their older stuff and a select few of their newer stuff.
Led Zeppelin: Misty Mountain Hop, Ramble On, In My time of Dying, Gallows Pole, Stairway to heaven, Kashmir... I dunno what else
Them Crooked Vultures: Elephants, No One Loves Me & Neither do I
Some Jpop, too, except I lost all mine years ago when I switched from an iPod nano to an iPod touch, so I haven't listened to that in years... I really liked Gackt and Hyde though. Uverworld, too.
Oh yeah, and all of the Naruto shippuden track basically ranks up here, too. I can't choose a favorite, man. I can list a billion though
(but my freaking iTunes deleted everything from it except music I purchased from iTunes
I will destroy Apple one day!)
Oh, and Death Note's soundtrack! Particularly Death Note (the song), Kodoku, Mello's Theme, L's Theme, Kuroi Light, and... Eh, I'm bored. That's all for now.
(Crap, I forgot Star Wars music too! Sigh...)