Pretty much all the music from Abe's Oddysee. I love listening to it and it makes me feel like I'm really in Oddworld.
And plus when I've had a bad day it makes me feel better when I listen to the music.
Abe's Exoddus is good too but yeah I don't have that same feeling like with AO.
I forgot about the main menu music in AE. Unlike the other music in the game it makes me feel like I'm really there.