1. "Nothing Compares 2 U" by Sinéad O’Connor
The original version of "Nothing Compares 2 U," tossed off by Prince in the mid-’80s and released by the purple one's protégés The Family, is a straight-up (and pretty forgettable) break-up song. But O’Connor’s version dialled the sad factor to 11, channeling the singer’s very real grief from the death of her mother five years previously. A superb vocal performance – the sound of naked sorrow – plus layers of weeping synth strings and an iconic, tear-streaked music video added up to one of the most successful sad songs in musical history. Pop music doesn’t get much closer to the bone.