Most FF's have a unique set of instruments or sounds used in their OST's atleast 4-9 do. Soundfonts are really good for being able to tell what FF you are listening to even without seeing the name!
My favourite soundfont is probably FFV i just like the synths in that one a lot. However my least favourite is definetly FF7's there are so many annoying instruments in there that they even ruin songs that are good. the worst is this weird sound that i think is supposed to be a violin or something but sounds like a cat being run over by a train on ice.