"Ray Of Light" is a key moment that marked a turning point in Madonna's career. Sonically, it remains one of the most progressive songs Madonna has recorded, with Euro club influences, electric guitars, electronic bells and whistles (it should also be noted that with its crossover appeal it brought mainstream attention to electronica.) It's one of the best and most unique songs I've ever heard.
But this is ATRL, so a dull and outdated song that "The Edge Of Glory" is will win (one of the worst songs she's recorded yet as well.)