I'm not really siding here with MB or BMW, but I think your assessment is fundamentally flawed. If you are doing a scientific experiement, for example, you want everything other than what you are testing to be as equal as possible. That way you isolate what it is you are trying to find out and nothing else can come into play. Now, with your BMWs. Since you are obviously a BMW enthusiast you know exactly what you are looking for when you buy one and you probably maintain them meticulously. With the MB you bought, I am assuming there wasn't much maintenence history that came with it. Many people on this forum absolutely preach that whenever someone purchases any MB, esp. older ones, that you get documented service history with it or don't buy it. I don't know how BMWs are, but with older MBs, they are wonderful, reliable cars if they have been maintained with every i dotted and t crossed. However, if they have been at all neglected, they can be hell to own. So, who knows how your 190 has been maintained? Who knows how it was driven in its earlier life? Also, this is just one model and one car.
Just like others here said, it is mostly preference. Just like Ford and Chevy, this "debate" so to speak will never end.