I haven't had a GLC 43. But did test drive one as was considering it. And the X3 is just on another level IMO. Was a merc fan boy and was disappointed by mercs interior quality compared to the X3. Also the M40 just destroys the GLC in terms of how it pits down power.
This is the story of every Merc fanboy in recent times. I shared this elsewhere:
All these things are apparently my fault or not quality issues on my facelift W205 (Car is just under 75000km and still on plan...). My FIL has had his W213 E Class since new and has barely any mileage (sub 25000km). Also has similar issues...
This peeling/bubbling steering wheel is not a quality issue according to Mercedes & neither is the electric window switch that has recently split and cut my finger when trying to use it 🙃 :
The clearcoat on the wheels (which incidentally cost more than my F90 forged 20" wheels) comes off in sheets like bad PPF. The best or nothing right? Anyway this is my fault... somehow... despite all my cars (in the case of the F90 with a much more 'delicate' finish as well) being washed the same way.
The plastics in various bits of the car age at different rates despite being (obviously) exposed to the same conditions. The most obvious is below. The tech told me to have the small bit wrapped rather cos it was gonna happen again even if I changed the entire moulding. Also apparently this is our fault... for apparently owning the car and choosing Mercedes over BMW or Audi 🙃
My wife who wouldn't even test drive F30/G20 has sworn off Mercedes. They are literally just designed to look good in pictures as I've said many times before. Good luck to anyone who is stuck with one of the all-screen ones... Mercedes will find any way of selling you garbage and telling you that it's good for you

I can only guess that people buying are purely buying for the name at this point. It ain't the quality or performance...
The saving grace is that the dealership experience has been great when trying to get things resolved even though they often get rejections from Mercedes. If not for that, it would have been long-gone. Let me not start with the experience when there is a motorplan claim...
The car above in this spec sold at nearly R1M. The equivalent now with EVEN WORSE quality, worse materials, worse ergonomics/design and a rubbish drivetrain (mine still has the 2.0T at least) is R1.35M. It makes the M340i look like the bargain of the century whichever way you look at it. People think I am exaggerating or that I'm a BMW fanboy when I say the quality and value on offer is absolute rubbish... I can only imagine what utter trash the cheaper vehicles and trims are. Mercedes quality was on life-support for decades and finally died after the W204 era.