Out of your list, I have owned BMW and Mercedes. BMW 318, 2 M3s, Mercedes C180, C220CDI and 190E. I didn't buy them new, I could never afford to, I'm a mechanic. I bought them when they were older and depreciation kicked in. To me, the BMWs were nothing special, they felt cheap and just had that badge that everyone seems to list after. The M3s were fast. Properly fast. Around 300 bhp, rwd and lsd. Good fun to lift the handbrake at 70-80 mph and do big slides but in terms of engineering, very basic. The Mercedes were in a completely different league when it comes to engineering and comfort. You don't really drive a Mercedes, you gently waft along in it. With regards to engineering, I was forever noticing little things that must have taken hours to design like the way the heater linkages were so over engineered when something simple would have worked or the way half the dashboard had to come out to change the radio. I've never owned Porsche or Maserati but I have driven them. The 911 was probably one of the worst driving cars I've driven. I'll never understand why they thought it was a good idea to hang the engine out over the back wheels. Very prone to snap oversteer. One wrong move and you're sliding backwards. The Maserati is a wired one. It's like a Ferrari but it's not like a Ferrari. Half the engineering is there but it feels like they got lazy come lunch time and wanted to come home so they started cutting corners.
When it comes to expensive cars versus really expensive cars, I think 90% of it is just showing off and saying I have more money than you because most of the time there is a cheaper car that will easily outperform it.