C280 question

I'm looking at used MB's and, for various reasons, have narrowed my search down to C280's.
Some quick questions:
For reliability and performance do you prefer the inline 6 or the V6?
For build quality, available features, etc., what are the model years to prefer or avoid? What are the "top 5" things that go wrong on these cars? What are the "red flags" that would make you immediately *not* consider a particular car?
Many thanks in advance for any advice you may wish to offer.
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