And by that I mean, what song would you consider to sum up the entire series? If you like, you can pick one from the series' soundtracks, and one from anywhere you like.

Obviously Final Fantasy is an obvious choice. Although Terra's theme and the FFVII main theme are both really good, I think.

As for a non-FF track, I honestly can't think of anything right now. I'm racking my brains but all I think of are funny gimmick songs.