It all depends on the installer, that can greatly effect the operation of a good unit. Goodman is low cost in part because they dont advertise while at the same time they have out sold every other brand in recent years. One problem with Goodman is that they stay behind the rest on new designs. The models they currently sell are pretty close to all other brands. As for Armstrong, I had an Armstrong gas pack that made it 26 years. It was still working great, I changed it out to save on gas bills. Does that say that Armstrong still builds a good system? Who knows, they all have a bad run of design flaws here and there. I always tell people to buy a brand that has a parts supplier in town because they all fail at some point. Nothing stops a Trane but UPS if you know what I mean.