which rotors(and size) are you using?
anything ive ever seen says skf is inferior to the fag units...however its splitting hairs really. Youd be fine with either.
I think fag makes the oem bmw units. the one thing the original bearings will have an advantage on most new things is they are actually made in germany. I think a lot of stuff is made in china these days and reboxed in germany and sold as "made in germany". Ive read this as being quite common.
Obviously in quality controlled facilities but it seems not quite as up to par as old parts used to be.