it is all in the driving and the maintenance.

i have most of the recent classics. a 6.9[50k]. a 1986 560sel[250k]. a 1987 560sec[81k]. a 1995 e320 cab[11k]. and a 1997 s500c[24k].

i like them all. they are different cars. the w140 is quieter, faster, less intimate. i think it outcorners all the others.

all the sound systems are ok if you are concentrating on the driving. what makes the w140's sound better is that the car masks more road noise. i am not sure that this is good thing when it comes to the issue of safe driving and the importance of auditory inputs.

the w126 is more like a lotus sedan. lots of immediacy with the driving environment. it is my favorite benz series. had benz added some additional acoustical isolation they could have manufactured this model for many more years and continued to have the most durable, most user friendly production car on the planet.

all things considered, i would find the lowest mileage, best maintained w126 and acquire it. personally i prefer the pre-1988 versions. no driver side airbag. a real glove box. and a useable center console. however, if you have to take a post-1987 560sel, the parts can be obtained to replace the passenger side airbag with a glovebox. and the damn center box can be removed.

if you are motivated, try to find a one-owner version with full maintenance records and less than 75k miles.

bon chance.