I am glad to see that low-light performance was prioritized. Otherwise, it is academic, as cost will keep me from buying such an expensive camera for quite some time, and if I owned such a wonderful instrument, might not want to risk carrying it at work, in the trunk (boot) of a police patrol car, when a cropped-frame camera is entirely adequate for the job.
It is somewhat entertaining to see comments from the loyalists of each brand. As I have indicated in the past, I have no such brand loyalty, being a fan of some EF L lenses, and some Nikkors. I have seen some stunningly detailed night images shot with my wife's D7000, and she has commented favorably on night shots made with my 40D and 7D cameras. Our first FF camera could be either brand.
Canon 7D2/7D/5D/40D/1D2N/M3; Nikon F6/D700/FM3A/1Dx/Coolpix A; Canon 40mm 2.8 STM, 135L, 50L, 35L, 50mm 1.8 I, 100mm 2.8L Macro, 10-22mm EF-S, 400mm 5.6L, 16-35mm 2.8L II; Nikkor 50mm 1.2 AI-S, 50mm 1.4G, 50mm 1.8D, 16mm 2.8D Fisheye, 180mm 2.8D, 100-300mm 5.6 AI-S, 45mm 2.8 AI-P, 14-24mm 2.8G, 24-70mm 2.8G, Micro-Nikkor 60/2.8G; Voigtlander 90mm f/3.5 SL II, Zeiss ZF.2 2/135 APO