The most important models, like the S class, the G class, and the AMG GT, still are the top notch in quality, quirks, and performance, but the other aren't like that

C and CLA class models are more like any other regular car with a nicer interior and maybe a better suspension, but at the end they even Renault engines (that aren't so well made), so they aren't so great than older versions.

All of this is AFAIK, so please correct me if there is any mistake.

Not in Europe. Mercedes was the Mercedes of cars when the S-Class was the pinnacle of automotive technology and only the rich and famous could afford them so they also had exclusivity going for them.

Nowadays, the S-Class is no longer nexus tech and thanks to cheap credit and rock bottom devaluation on the second hand market, they're not at all exclusive that even in the poorer parts of town where I live, there are lots of Mercedes and in Germany they're used as taxis.