Why not go for both? I mean, there are some excellent FF songs that have both a piano and an orchestra, such as Aerith's theme (FFVII Reunion), Love Grows (FFVIII FLWV), Dagger Cuts Her Hair (FFIX OST Plus), Zidane and Dagger Separate (FFIX OST Plus) and At Zanarkand (FF More Friends Concert). And while they aren't FF songs, the march ending songs for KH and KH2 are both very well done, "March Caprice for Piano and Orchestra" and "Fantasia Alla Marcia for Piano, Orchestra and Chorus".