To be honest, for some tasks, even some FF cameras can be not good enough, not clean enough at base ISO, too low-res, lacking DR, etc. While it seems like most people think that all cameras are the same at ISO 100. They are not the same and there is plenty of noise at low ISOs, which is relatively easy to filter, but not without compromises. There is no end to this debate, because some people are shooting tiny little snapshots (for social networks and stuff) and some people are more demanding, they want to view it large, large prints, poster size - wall size, high quality, or crop-in to the extremes. Crop sensor potential fails much sooner at much smaller sizes, despite that it surpasses film quality, because FF potential is more than twice superior. You can try to measure and compare all kinds of photographically relevant qualities, like DoF, sharpness, contrast, color, dynamic range, bit depth, etc. But in reality there is only one (to rule them all ), it's the ability to gather as much correct data as possible - THE image quality. It doesn't matter if you need all of it or you don't, it will always be the benchmark. Given the same level of technology, larger sensor area will always gather more light to produce more information. All that waiting for APS-C to win is like waiting for '2' to become more than '5', which will never happen.