So far I have tried Silverstars, then Bimmer Xenon 55w, then Bimmer Xenon 75w and now 5000k H7R HID bulbs.
The best brightness of the halogens was the Silverstar. The road looked bright, even and white, however looking at the car from head on, the lights only looked slightly whiter than the stock bulbs, still yellowish looking
The Bimmer Xenon Halogens looked great, but had poor light output. Even the 75w did not perform well
The HID's installed in the car now of course are the brightest, and so far no error lights or problems. I drove the car for about an hour today with no errors.
All this could have been avoided if BMW offered the Xenon upgrade for $900 on the 2012 model cars, like they are currently doing on the 2013's.