I have apexcone ellipsoid headlights w/ 4300k HID. Side by side you can't see any difference between the apexcone, and the major competitors (depo,zkw) Apexcone uses a slightly less brittle plastic than the depo's so the tabs are less likely to snap off while installing. ZKW's are the best, but you pay a premium for them.
I recommend DDMtuning if you don't want to pay too much, but I'm probably the only one on this site that does. If you want some less biased reviews head over to bimmerforums.com, and you'll get a more well rounded review.