I work at a very busy hydroponic store we sell hundreds of ballasts all the time. Phantoms are the BEST have never got a return yet and already sold a ton. Lumateks have had quite a few returns, mostly if run on super lumens all the time they burn out (although they have a pretty nice warranty which most people take advantage of). Quantum we dont sell alot of so hard to say, and nextgens sorry to say but are known to burn out regularly after 6 months to a year.
One nice thing about the lumateks over the quantums is they are completely enclosed, no pass through fan for cooling so no chance of dust accumulating inside the unit.