I'm very biased against VWs. I've only been in three newer ones and only one of them had nothing wrong. One of them developed the ignition coil failure, among other things (many many other things, numerous check engine lights and electrical failures), one of them revved all the way up to the redline without the driver touching the accelerator pedal. Scary stuff. When my friend brought the car in to get the coils replaced, the only replaced the bad ones (despite corporate knowledge of something being defective) AND it took over two weeks to get the parts. VWs look impressive, but I'm waiting to see how they'll weather over the next few years.
Mercedes might have their problems now (and according to JD Power, they DO have problems), but I know that they have a heritage of making good stuff and are capable of bringing their quality back on-line. I'm not sure I would buy a new one yet though. Not that it matters, I have other expenses
Alex