As the proud owner of two of them, I'm very biased. But I just don't see them as having a weak spot. (No, I don't consider the SBC a problem at all.)

Rossafuss over on Benzworld has one with well over 450k miles...drives like new.

I suppose a case can be made for a 14-15 E250 Bluetec. But you're also paying 4x the price.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles
06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 142k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife