Bill this is a area I can share a lot in i use Midi file all the time I do like style play but I find Midi file offers a better fuller sound if you are acomplished in a instrament ie Piano or guitar it offer you the oppertuinty to play fuller arang while playing you main instrament

now the midi file differ greatly with different keyboards

I find Yamaha the best at playing midi files by a long shot

yamahamusicsoft.com very good site also MIDI Spot as well both the same really
midi spot being my fav here if you use a Tyros or Psr series keyboard they do the best job at lyric and chords and the ever important Transpose button
back in the past Roland G70 did a great job at tume 1000 files woth chords and lyric this will give you freedom from sheet music and i pads ect i support Midi Files over Mp3 any day of the week for the above comments all true .