Diode Dynamics is good.
The main issue with the cheap bars is that the REASON they are cheap is zero QA/QC. Poor solder, thin wires, no gasketing or poor gasketing, weak mounts, galvanic corrosion, water infiltration, etc, combined with zero engineering of the optics or LED, drivers, etc.
So they claim to have whatever lumens the combined number of lumens for the combined max output of the LED from the factory (Cree for example) would be, IE: Max out put of 1,200 lumens at maximum drive levels with optimal heat sinking, etc...per LED, times the number of LED, and then pretend that's what the light puts out.
But it might be closer to 200 L per LED than 1,200....because the thermal paths, drive levels, etc, are NOT optimized...or even present, as when the leave off a heat sink, etc.
The LED are in shallow reflectors, or use plastic clarco's, etc, so all the light is in a bright pool right in front of you, so it LOOKS "bright", but, hurts your actual ability to see at night.
The better LED bars use deeper reflectors, weather sealing, optics, heatsinking, drivers, etc...and throw the light farther, out where it can do some good, etc.
So, it mostly means buying a real LED light bar, or a toy that looks like one because the toys are cheaper.