I guess it kinda depends where...
back in Jakarta, a W123 280E w/ a 5-speed is not rare at all...
even a W124 300E Sportline w/ a 5-speed is so common...
in fact... 280E (123)'s with Auto trans is considered the rare ones... (I saw one priced like a W124 300E)
they actually put a badge (where the Turbodiesel would be) that says Automatic.. and yes it's factory.
but... the 123 is very famous among car nuts.. even if they hate Mercedes-Benz... - They call it 'Tiger'... I don't know why.

oh... the 280GE! Yes the mighty G-Wagen...
those cars run around the streets as if they were VW beetles... not taken care of, rusted away... and they cost almost nothing!

for some reason.. there are not that many W126's... in fact.. I usually see only one in a year... kinda weird.. but there's a lot of 140's.
but, if I were to guess..
I'd say...

500E
190E 2.3-16/2.5-16
W116 6.9
W108(?) 6.3

but I do feel that the 123 might find a place somewhere...