don't get fooled by the names of the light color. Just concentrate on the K value.
The best usuable light output is 4300 - 4700K, but is a little yellow (like sun light).
The nicest light, but still very usuable is 5500 - 6000K, which is very white-ish.
Anything above that is blue-ish (7500 - 8500K) or even purple (10000K) and is only for looks.
Also, do not buy the cheapest HID bulbs you can find, but go for quality stuff.
The cheap bulbs are from Taiwan or China, and will discolor in 6 - 12 months (if they do not fail). Go for a big brand like Philips, Catz. or Bellof, and this time, pick the ones with the correct K value.