Ohh, I misunderstood, I thought you were going to give us a list to choose from...
GAH the enormity of the music industry is to large, to single out one song would be impossible for me...
My favourite song is absolutely without-a-doubt Chasing Cars by Snow Patrol. But I listen to the 70's, the 80's, and today's music (and the Beatles are legends; my 60's favourite).