The best ever diesel in my experience is 1995 E300 (W210).
They are really quiet and gives petrol driven engines a run for the money.
But now with the latest CDI (common-rail diesel injection)engines they are a gem from standing start.
The side effects one has to bear with is the rocking noise the engine makes during idiling.
If they are available in your country you should test drive them.
1995 E300 Diesel (W210)
1999 E250 Diesel (W210)
2000 S320L (W140)
2001 V220 CDI (Vito/V-Klasse)