I have used Mann for years but recently switched to Mahle.
Just order a whole bunch of stuff from autohausaz.com, as long as > $75, shipping is FREE.

I put together a photo of Mahle vs Mann, you can see that the Mahle is better constructed in my opinion:

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1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT