“November Rain” by Guns N’ Roses.
My personal favorite power ballad is "Don't Know What You Got (Till It's Gone) by Cinderella. A few years ago when I relocated to NYC for work, that song played on the radio as I was leaving my old house for the last time up in the Boston area. It was already a favorite song of mine but just serendipitous that it happened to play at that particular time.