Celes' opera? Though I guess that can't really be a joke answer since it was actually done, and didn't sound nearly as good as it did in my head during the actual event in the game

I almost want to say Luna's Boat Song from Lunar, since it's one of the first actual songs I heard in a game, and it was campy and cheap and completely endearing. Not nearly as well done as some things done later in gaming, but it came from the heart and was performed from the heart in the earlier days in gaming

Outside of that, I feel like one of the Tales games had a song I adored. But I can't remember if it was Graces, Xillia, or Zestiria