I own a 95 E300 and a 97 E300. The 95 has never been in the shop. The 97 has been there for a leaking injection pump, 4 times for check engine due to bad manifold resonace flaps, once for bad switchover valve, once for no start due to K-40 power supply relay, and once for burned out side marker light assy.
The mechanicals of the 95 are clearly the best. The 124 amenities suck though. The heating/AC fan system is loud, the old style wheel temp control is out of the dark ages, and the car is missing little things like reading lights for passengers that even my 1983 Audi 5000TD had. I love the superior creature comforts of the 97.