I have one of each but they differ quite a bit in age and miles. I've had a 1991 300CE, 145m for 5 years and a 2000 C280, 55m for a little over 2 years. I have an average of $1300/yr in maintenance and repairs costs for the 300CE and about $570/yr for the C280. The 2 repairs I've had for the 300CE that I would consider "w124" problems are the tumbler and the pretty expensive head gasket. I've changed the CPS on the C280 which I consider a "W202" problem. I think the W202 is clearly a superior car with its electronic transmission and electroinc HVAC.

glenmore
1991 300CE
2000 C280
1990 LS400