I think it depends on the car. On my W126 I installed the cheapies. But on the W210 I went with OEM Sachs. They were only $335 with lifetime warranty, and the car rides like new. Bilsteins were about the same price, but I figured the first set of Sachs lasted 180,000 miles, so why mess with what works.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280