Some people used Valvoline. Not sure how good it is, or how it will last, or if it will affect the transmission negative.
One point I have to make: they list all those BMW approved ATF's, which are all different p/n (11 digits per BMW) and have different applications (different transmissions), yet this magic Valvoline MaxLife can be used for any of these?
Attached is the BMW ATF approved list of oils. Call it the BMW ATF bible if you will.
ZF Tranny Oil.pdf
Cheers