Are 80plus power supplies worth it? Extremetech just that question recently. Based on their conclusion, not usually, at least not solely for power savings. But it’s an easy way to get a box built to stricter tolerances with higher-quality electronics.
I like to buy power supplies in person. First I look for a recognizable name, like Cooler Master, Thermaltake, Corsair, OCZ/PCP&C, Seasonic, etc. If at all possible, I avoid the $15 cheapies, and anything made by anyone who also sells $15 cheapies. Quality makers generally aren’t interested in competing in the $15-$20 space.
Second, I go by weight. Costly electronic components weigh more than cheap ones. Big capacitors weigh more than small ones, and capacitors weigh more than empty board space. If it feels like a brick when you pick it up, it’s better than if it feels like a plastic toy. Yes, a company could cheat on this test by putting cheap stuff in a thick, heavy gauge box, but most don’t because they’re trying to save every nickel they can.
In the event of a tie, then I’ll buy an 80plus unit if one is 80plus rated and the other isn’t.
Then again, at and above the $50 price point, most are, due to demand. So if the point isn’t moot yet, it’s likely to be soon.