I dont know really :O , I would perfer to have BETTER midi quality then have buggy MP3 quality (not to say that it will be, but you still have to have the mp3s tho dont you?).
But seeing how now ones bothered to make better midis, there seems to be much better mp3 remixes/remakes of ff7 music, so i guess the volume of better media is really the deciding factor. Unless someone (maybe?) makes a new collection of FF7 music, or someone finds some great FF7 music on the internet (theres gotta be some somwhere?).
Until then i dont care if its MP3 or MIDI, i just want better music with more instruments and more like a live orchestra....