brightest and bluest is a contridiction. If you want bright get 4100K if you want blue get 6000K or above. i recently went from philips 4100K(85122) to 6000K(85122wx, also know as ultinons) and the light output is noticably less. They color is much "prettier" but the output is most certainly not as bright. I've seen several cars with 7000K and 8000K bulbs and those are worthless in my opinion. I'm close to taking my ultinons out and getting some 85123(5000k) or just ptting my 85122s back in and calling it a day.

Are you wanting HID for the cool bling bling factor, or are you actually concerned about seeing better. If you want the BRIGHTEST HID that give you the best visibility hands down 4100k. If you want a blueish tint get some audi projectors like I have, and everything above the cutoff will look blue, if it's not blue enough tweak the shield and you can get even more blue without sacrificing much visibility. And in the rain?? 6000K SUCK compared to 4100k in the rain, I just had three rainy days in a row, and that's pretty much why I'm ready to put my regular 85122 back in.

Also whomever said S2000s come with 6000K is mistaken, it's the projector and shield that give it that effect, the light itself is indeed 4100K.

It's up to you though, whether you want hid to see better or just to be cool, the color choices are there.