The M119 is one of the most over-engineered engines to ever sit in the bay of a passenger car.
The best W210 in my opinion is the 1997 E420. While the M112 and M113 engines are superb low emissions engines that are pretty much bullet-proof save for the harmonic balancer, they just don't have the same sound/feel/some-intangible of the M119 DOHC V-8.
The E420's can also be picked up at pretty decent prices now. I think anyone that is selling their cherry W210 E420 is kinda nuts, but that's a bonus for us enthusiasts.
1998 C230 "Black Betty"