i dont care about tint all i want is lumens per watt
Cool white outputs more lumens than neutral white, which outputs more lumens than warm white.
how about cree 6500 k vs sst 6500K which is better for lumens per watt
I don't know individual emitters very well, but Cree is generally quite efficient.
Very green tinted emitters around 5200-5700k will be the most efficient. Large die, domed, low CRI. Cree XHP70.2 OR 70.3 is probably the most efficient in a 7070 or smaller footprint.
I agree with Jared. The XHP 70.2 is just so efficient with the large dome and abundant phosphor. For ultra low power Leds, there might be something more efficient but I doubt it. The XHP 70.2 has over 200 lm/W when driven under 1A.
Overall, you still need to qualify it with a current range. The XHP 70.2 will not be the most efficient over 20A because the multidie Leds will beat it.
That's interesting about the XHP 70.2
I have one flashlight with that emitter, and it's my favorite flashlight and emitter.
There is a tint shift with the XHP 70.2 that some people don't like, but it doesn't bother me.
Another vote for the XHP70.2. My Thrunite T2 with a single XHP70.2 can run for hours on it's high setting. A ton of light and some serious runtime out of that diode.
Samsung and Everlight reach 230 lm/W with their mid power LEDs driven at really low currents. This is the best that I’ve seen. And I think it actually is with CRI80.
Also, depending on what application you are going after, mid-power emitters are a really good option. 200+ lm/W is available in abundance for very little money. Definitely where the value is at for diffuse lighting apps.
Well that was easily the best summary I’ve ever read. Thanks Quad 
yes, we agree.
thanks Quadrupel.