And perceptions of quality are often wrong. Going with your Ford example, we have a '97 Ford with 220,000+ miles and no major problems. Yet every rental Toyota/Honda we have had has been a piece of ****. Now of course you can say the rentals were abused, but I think that points to the real cause. If you take good care of your car, in most cases it will take good care of you. The media loves to portray unreliable "brands", but maybe it should talk more about unreliable driving styles, maintenance, etc. So, I am not saying either of those brands of MB are 'good' or 'bad', but rather to be wary of labeling them as either without a good bit of evidence to back it up.
Edit: and if going for age, also have an '88 Pontiac still going strong.