Too many to choose just one.
Sometimes i want classical, sometimes rock, sometimes good old gospel, sometimes bluegrass, sometimes anything a capella, sometimes solo instrumental of any sort ... sometimes blues, country, just about anything

I know I am weird, I have my own personal soundtrack that runs through my head. You can ask me any given moment what song is running through my head, and I can tell you - although I might have to sing it to you, as I can never keep track of the names of classical pieces that don't have words.