Regards looks, style?
W210, although smallish, is among the best of the best of all time Daimler-Benz design. The retro/throwback, early 1950s facelift recharged the mid-size Daimler-Benz brand.
Worst? Hands down the Army-tank styled W124. Darkest style ever made in the mid-size category.
W140 - Ugh.
W212 - save your money and buy a used Cadillac DeVille of the same vintage. Drives exactly as a Caddy.
W123 - so homely, they grow on you.
W126 - another best of the best Daimler-Benz ever created.
W116 - another best of the best Daimler-Benz ever created in modern times, 1960s on forward........
Almost ANY model SL- terrific, timeless styling.