4300-4800 is what OEM manufacturers use.
The point of upgrading lights is, to me, to improve visibility at night. You'd want to get a 4300k HID kit as these will provide the most light onto the road and give that nice crisp white Xenon light.
Ignore people online saying 6k is white , 4300k is noticeably white with a blue tinge.
6k is blue and for people who drive Corsa's IMO