whichever one fits your room and budget best. A good quality light of any type will grow great plants. Today's best light, I would say it is a close toss up between Cob Leds and CMH with quantum boards maybe about to knock Cobs off the led throne. Led side has a much higher start up cost but will recoup the money after a few years of use IF you don't upgrade them before they pay for themselves (hard to do with them changing so often). CMH is looking really nice and a long needed upgrade to old metal halide technology.