I've always loved the w124 coupes. I've also always loved the W126 Coupes.
As far as the car that I think was built the best and the most reliable, a 124 in any flavor would fit the bill.
Now as far as a car that I think has stood the test of time as far as styling goes. you can't beat the 107SL styling. a style that was around for near 20 years.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.