Many people would agree with you in this. My personal experience with the W126 version of the S-Class (1987-1991) is a little different: if you can locate an 300 OR 420 SE OR SEL you have a vehicle that many opine was the last Mercedes built to an engineering standard vs. to a price point.
Both my 420SEL's have over 170K miles on the original bottom ends, the '91 has original engine & transmission, the '87 has had a tranny rebuild (by previous owner @ $2,500) and a top end rebuild (ditto @ $3,500). The '91 got 18.7 mpg on its last tank of mid-grade in mixed city/highway driving. A/C systems have been converted to R134, one has a broken sunroof track (the oldest S-Class with the original sunroof rails my mechanic has ever heard of), but the interiors are fine and everything works with the exception of the outside temp LCD on the '87.
I read the comparison tests of the BMW550i, E550, Lexus GS460 & the new Supercharged Jag and just shake my head: smaller cars, les gas mileage, insurance through the roof, $1000+ for a set of tires (typically with different sizes front to rear), more electronic alphabet-soup [censored] to go wrong (after the warranty expire$$$$$$), a lot of which I would never want to begin with (I-drive, CATS active dampers, etc. ad naseum).
Just imagine what it will cost to get a 7 or 8-speed automatic tranny worked on after the warranty expire$$$$$$?
An engine rebuild or replacement?