I'm not a diesel expert, but from what I've read, the 240D is the most reliable MB to be had, without exception.
The biggest tradeoff is that it's slooowwwww...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car