My 96 W210 runs great.
Currently with 166K miles this car has been pretty good.
I still enjoy driving it. There has only been some minor problems with the ignition coils which were replaced.
This car does not have the wire harness problems like the previous M124 models but it does have the same head gasket problem.
Mine has started to leak recently so I will have to get it fixed.
The 4 speed transmission is fine. I run it to 85 - 90 on my long trips and the engine rpms are around 3-3.3K. I get about 20 - 21MPG combined city/highway (30/70) driving.

I am planing on keeping mine as long as its financially feasibly.

One thing about the 96-97 models are they are really inexpensive to purchase compared to the later years.

Good luck in your hunt.