QB LED is most effecient so far, meaning it takes the least amount of wall watts to produce X amount of light. QB's utilize several individual mid power LEDs per light. HLG I believe was the initial trend setter with the mid power arrays, and they called their lights "Quantum Boards" or QB's. It's now a common term referring to any mid power LED array.
COB LED is second most effecient, closer to 90% of mid power LED, but uses less space to create the light that QBs use. Because of this more concentrated power consumption they can produce more light per area than QB or mid power. Because COB have more concentrated power, they need to be hung higher and heatsinked pretty much at all times. They can produce more light per area, but take more watts to produce that light compared to mid power.
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If you're used to HID I think COB hang heights and light intensity will be more translatable to you, but QB is very good. Both can be managed with a mechanical timer. HID manipulates wall juice with HID ballast then pumps to HID light, LED manipulates wall juice with LED driver then pumps to LED light (figuratively). Generally speaking, it costs about half to DIY your own version of a premade commercial light, but there's always tradeoffs.
HLG
Pre made versions of the QB setups rivaling/surpassing HID
Timber Grow Lights
Pre made versions of the COB setups rivaling/surpassing HID
ARROW, Digi-key, eBay, Alibaba - Places to source DIY from
DIY COB/QB combo
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