To the orignal poster, choice between 124 & 210. To choose betwee the lesser of the two evils
my vote goes to W210!
Reasons:
W210 maint. cost is considerably less than W124
Improved Transmission 5 speed
Improved Steering Rack & Pinon
Possibly Improved Suspension
Improved Climate Control/Audio system
No Headgasket/wiring harness issues, possibly reduced evaporator failure
Improved electrical system
W124 has the ageless classic styling, with an unlimited budget, I would go with the W124 and make modifications to improve the weak area's!!