I prefer the Bose 8 speaker system in my C-Class to either the six or ten speaker systems I have encountered in the BMW 7-er cars. I agree about those systems' distortion at high-ish volumes.
My C-Class is a very rewarding car. I wish I had spent a bit more on a V-6, but then it would have cost more...
1999 SL 500
1993 320 TE
1986 500 SEC