I have been running these for two years and like them a lot:

Bimmian Xenesis Tru-Match Bulbs for BMW 1 3 5 6 7 M X Z Series Coupe Sedan Convertible

Short of going HID, this is as close as it gets for bright, white light. I have them for Low, High, Fog and License Plate. The lifetime warranty doesn't hurt either....had one license plate bulb replaced so far.

Andrew first brought these to our attention several years ago.