The cruel lab rats at DxOMark have completed a test of the latest Nikon D5500 APS-C SLR. The comparison page shows that you would have to be suffering from a serious vision impairment to want to purchase a Canon 70D. The Nikon offers 2.5 f-stops more dynamic range (ability to capture both shadows and highlights in the same photo). The Nikon also has somewhat better low-light performance. The Canon SLR scores about as well as a Sony pocket-sized point and shoot camera.
Who wants to take a crack at explaining how Canon continues to be the market leader in higher-end digital cameras? (press release)