I totally agree with you. I have been through the maintenance problems with my car, We've learned the lesson quite well. Nowadays, if you want to get something right, do it yourself.
The W126 is stoneage compared to the W140, but like the W140 it has presence, character. The build quality I'm sure is second to none in both of them.
The problem is finding a good clean car for a reasonable amount of money. If a car, be it any make, if maintained properly will last for decades.