It really depends on what's important to you. I believe it is unfair to compare the four in the W202 (C-Class) to that in the W201 (190E) as they are different animals. The W201 got the M102 whereas the W202 got the newer M111. We have lots of them in Australia and they are very reliable and economical engines. A bit "buzzy" (mechanically noisy) but I would not consider them rough. My parents have one in a W210 E230 and my wife's parents have one in a W202 C200 and both are absolutely reliable (I can't say the same for my father's E320 coupe with its M104). The older M102 in the W201 was not as reliable suffering similar head gasket problems to the M103 and M104 sixes. The C280 with its M104 generally won't offer the reliability of the M111 due to head gasket and oil leak problems. It is also more difficult to work on and will be more costly to service. In return for this you get better performance (at the expense of fuel economy) and the smoothness of the six. Whilst the late M104 is not as quiet as the old M103 due to induction noise on an open throttle, it is not mechanically noisy as the M111 four tends to be. Comparing the old M102 four to the M103 six was really an easy choice (as the M103 is just superb despite its problems). With an M111 versus M104 choice it is not so clear cut. Go for the C280 for performance and smoothness. Go for the C220 for reliability and economy.

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.