OT, this is like asking someone what's thier favorite icecream - everyone likes a different flavor.
I personally like the Phoenix 14k Double ended bulb - but that's my flavor. many others like single ended bulbs at 10k, 11, 12, 13, 14, 15 and 20k in XM, Coralvue, Aqualine Bushke, Ushio, IceCap etc.
So many flavors.
What are you trying to accomplish? Visual Color? Coral Color? Maximum growth? each has an ideal temperature.
Hope that does more help than confuse.
House