Koni, KYB, Bilstein make good products; I won't knock them here.
For my money I would buy Monroe.
Every car and every driver is different; what's best for one is not best for others.
Unlike a lot of M-B owners, I don't insist on all German or all original stuff for my cars. There is reputation and then there is reality.
A good example is bearings. I have seen some bad quality issues with SKF, FAG, etc.; in most cases you cannot beat Timken.
Have fun working on and driving your ML.

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Now you're suckin' Diesel!

'88 300SEL
'92 300D 2.5 Turbo
'96 Lincoln Town Car. The Jazzmobile.