7 inch HID, either 35 watt, or total white out, and go for 55 watt.
The only colour I would opt for a colour output of between 4,500k and no more than 6,000k
4,500k is delivers more lumen (light output) than 6,000k, however 6,000 gives a perceived more lumen output with it being more whiter light.
They are the same bulb incidentally, just the bulb is allowed to eat more watts, via whichever restrictive ballast you fit, ie, 35 watt or 55 watt.
Lamps driven via a 55 watt ballast, don't live as long as lamps driven via a 35 watt ballast.
Typically, 50% longer life with the 35 watt ballast.
I genuinely feel 35 watt HID is the way forward on a 7 inch reflector.
Gra.