"Best" is hard to define without criteria. Moreover, I'm not an expert in this field, but I know enough to throw some things out here. First, nextlight's primary focus on the mini is efficiency, so if that is your concern, also take into consideration the efficiency of their included AC-DC transformer and the light : heat ratio of the output of the mini. Also, I chose the F564B's due to them fitting my tent idea's design well, are upgrade-able to a 4x4 area if I do that in the future, cost less compared with other LED strips currently, and they cost less than a pre-built system that would give me 250W. In some aspects, these LEDs can be counted as the "best," though not according to every criteria, such as ease of setup, safety (mostly during setup, but what if when I wire things up that I forget something and then 150+ volts are surging through the system and potentially harm someone, yikes!), or the amount of tools required to install and set-up (not everyone has a soldering gun).
Define some criteria to what's important for you? Higher upfront costs for lower maintenance/monthly costs? Upgrade-ability to future builds and tents? Convenience of setup and use?
As to a quality comparison between the two lights, I cannot comment on that. I simply would not pay that $500+ for something I could build for $150. Also, I couldn't find a good datasheet for the mini.
Lastly, think about defects, damage, and blow-outs: which systems are easier to replace? It looks like the mini is active cooled, which means there is potential for the fans to break; if the fans break, would you have to replace the whole unit? If something breaks in my setup, I only have to replace a 5-10 dollar fan (though I'm not using fans, so I guess not hehe)
