If you're looking to grow plants to maturity, the ideal lighting range is probably in the range of 25-50 watts per square foot of tent. With that said, most plants will grow fine in less light. If you're just looking to keep stuff alive in the winter then you can get away with very little. I moved last year and I don't have anywhere near enough winter tent space, so I've got probably a hundred plants or so that have been just sitting in 24/7 darkness for all of this past winter and the majority are staying alive just fine. I've got a 100W 2x2, 34W 2x2, 430W 5x5, and 100W 4x4 currently and I just try to orient the plants based on how much light they want. I like the SpiderFarmer bar LEDs as the prices aren't too bad, though I also have some HLG QBs and a cheap 34W GE LED bulb from Amazon that seems to perform just as well as the 100W HLG board in a 2x2. I was originally looking at Kingbrite since it's supposed to be the best in terms of price-to-performance, but the time and extra cost of shipping from China kind of ruins the value unless you're ordering in bulk or are fine with a potentially long wait.