Fortunately I have the possibility to listen to all three sound systems. I played the same music on all of them (mostly rock like RStones, Bad Co, Supertramp, Credence, but also Petrucciani and the Classics) and the conclusions are simple: DON'T GO WITH THE STANDARD as the speakers are clearly limited.
The HiFi or the medium range system is good, though if you're into music and looking for a flat sound, neutral and clear (the way the musician would like you to hear it) you might want to consider the hi-end sound system. It comes with Dirac tech (amp) and an equalizer which will help you get closer to that neutral sound.
Before you choose you might want to take a look here:
http://www.bimmerfest.com/forums/sho...essional+audio