LED-Dilemma (Spider Farmer / VIVOSUN)

Simple answer is use both lights and adjust the power accordingly to the plants needs.

i'd probably use both and dim them... 200w is a bit on weak side for 8 sq ft unless you are growing autoflowers, but also the distribution of light won't be so great in corners with 1 light. Autoflowers can run on 18/6 or 20/4 with either of these lights -- i'd go with the higher efficacy if you are set on using one or the other. With photoperiods, you probably want closer to 300w, so each at 70-75% to start... (12/12 schedule, so in vege 2/3rds of that... 50% each in vege) for both configurations expect some trial and error -- observe plant and based on growth pattern, adjust light further... proper node spacing is your guide i gave the flower needs, but if you learn through trial and error on 18/6, you simply take what you learned and multiply by 3/2 (150%) when you switch to 12/12. Keep same hanging distance and it'll be the same DLI, give or take an insignificant amount. So if you find 45% works best with both, crank it to 67.5% in flower. i've simplified a bit. Since these lights probably don't have the same efficacy, which results in different wattage needs to deliver same DLI. if the reasoning sounds odd, go read about Daily Light Integral. This is a measurement that is apples to apples regardless of hours of operation or size of canopy. It is the best way to perceive this.