FFVI. None of the others felt nearly as epic to me as that one. And nothing beats seeing Kefka descend from the heavens for the final fight, with Dancing Mad playing in the backgroud the whole time. In fact I think Dancing Mad alone is what really sold it as THE epic battle of the game for me. FF4 strangely enough, with only one battle at the end, is the only other one that felt epic to me. Other than those two, FFVII was the closest to driving home the fact that I was fighting to save the world. None of the other ones have really been able to drive home that feeling for me.