Here is a list i made looking at the most powerful & efficient LED fixtures currently available. Cheap LED fixtures just do not compare to gas discharge at all, they have their place for small scale grows but they are most definitely, less efficient.
Fluence
Spyder X Plus
PPF 1500 umol (True Measurement)
2.3umol per watt
$1500
$1 Per umol
Spyder X
PPF 810umol (True Measurement)
2.5umol per watt
$900
$1.11 Per umol
Spectrum King
SK602
PPF 1376umol (Calculated)
2.15umol Per watt
$1349
$0.98 Per umol
SK402
PPF 924umol (Calculated)
2.15umol Per watt
$779
$0.84 Per umol
Kind LED
K5XL1000
PPF 850umol (True Measurement)
1.3umol Per Watt
$1900
$2.2 Per umol
K5XL750
PPF 560umol (True Measurement)
1.3umol Per watt
$1400
$2.5 Per umol
Black Dog
Phytomax2 1000
PPF 1600umol (True Measurement)
1.5umol Per watt
$2250
$1.4 per umol
Phytomax2 800
PPF 1280umol (True Measurement)
1.5umol Per watt
$1949
$1.5 Per umol
Phytomax2 600
PPF 960umol (True Measurement)
1.5umol Per watt
$1549
$1.6 Per umol
Phytomax2 400
PPF 640umol (True Measurement)
1.5umol Per watt
$1099
$1.7 Per umol
Chill LED
Gen2 800
PPF 2000umol (True Measurement)
2.6umol Per watt
$2000
$1 Per umol
Gen2 600
PPF 1900 umol (True Measurement)
3umol Per watt
$1499
$0.8 Per umol
Gen2 200
PPF 615umol (True Measurement)
2.9umol Per watt
$599
$1 Per umol
NextLight
Mega
PPF 1400umol (Calculated)
2.15umol Per watt
$1695
$1.2 Per umol
Mini
PPF 255 (Calculated)
1.7umol Per watt
$595
$2.3 per umol
California Lightworks
SolarSystem 1100
PPF 1700 (True Measurement)
2.2umol Per watt
$1599
$0.94 Per umol
SolarSystem 550
PPF 888umol (True Measurement)
2.2umol Per watt
$799
$0.9 Per umol
SolarSystem 275
PPF 439umol (True Measurement)
2.2umol Per watt
$489
$1.1 Per umol
Here is gas diacharge technology for comparison
600watt HPS
PPF 1100umols (True Measurement)
1.8umol per watt
$200
$0.18 Per umol
1000watt HPS
PPF 1400umols (True Measurement)
1.4umol per watt
$250
$0.18 per umol
1000watt DE HPS
PPF 1700umol (True Measurement)
1.7umol per watt
$300
$0.17 per umol
600 watt Metal Halide
PPF 780umol (True Measurement)
1.3umol Per watt
$200
$0.25 Per umol
315 watt Ceramic Metal Halide
PPF 491 (True Measurement)
1.5umol Per watt
$500
$1 Per umol
As you can see, these high end LED fixtures are more efficient than traditional gas discharge, but the cost per umol is much higher. Which is why large scale commercial growing is still mostly gas discharge. Its very difficult to recover investments for higher priced fixtures over a rational timeframe. Which is why, until the cost per umol comes down (which through haitz law it will, eventually), gas discharge is still top dog for the time being.
If you just want the best of the best, then i recommend either fluence, california lightworks or nextlight. This is because of both their great efficiency but also cost per umol. Although chill LED has great efficiency, these fixtures are more approapriate for large scale cultivation. Not small scale. But they would still do well if used approariately.
Please check my articles if you have not already, there is plenty of good information surround light technology and plant science.
If there are any further questions, please feel free to ask.