If you have the room, from 3 series cells, I like the sst-90 driver from Dx. It does a solid 5.5A on the cheap. As for emitter DeftX and Black Bullet are both using XPG2 de-domes with the wavien collar. I'm not sure if there is anything better than that right now. My current thrower is 5.5A XML2 with the 78mm Aspheric. I tried both an XML2 and XPG2 on copper at 5.5A. The XPG2 was a very small almost unusable spot size. The XML2 is about 4 times as big. I also smoked the XPG2.
In a real life situation I had The XPG2 in the back yard with the dog at night. The sneaky bugger went under the fence and started cursing around the bushes. I had to run inside and get a different light that would light up more than a 1 foot square.