I've tested a number of different led lights the last couple of years, both for 12V and 230V, and my conclusion are that the most important thing are that the leds should be driven with a current limited circuit.
This is specially important for leds connected to a battery with solar/wind as a charging source. I've had smd led lights with 3 leds in series with a resistor, and when outside temperature where my battery are drops below -10 to -15, the bulk charge are easily over 15V, and some of those leds got so hot that the solder melted, and the smd leds just dropped off...
I've now replaced all of those led lights with series resistor with led lights with current limiter circuit built in, and most of the lights are above 65lumens/watt; the best one @ 90l/W...