The Canon EOS-7D Mk II and EOS-6D cameras were announced in September (2014) and September (2012) respectively. I have picked the EOS-7D as the best APS-C camera four years in a row and I eagerly waited for the 7D Mk II's arrival. I took the new camera to the sub Arctic for some vigorous field testing last month and wrote an extensive review on it.
Over the last few years, I have been asked by photo enthusiasts which is a better camera, the Canon EOS-7D or the EOS-6D, and now the EOS-7D Mk II. In the interest of full disclosure, I am not a fan of the 6D. The 6D is a good camera for those who want to get into full frame photography on a limited budget. It has an older sensor of roughly the same megapixel as the 7D Mk II. The native ISO range (64-5600 vs 100-16000) and burst rate (4.5 fps vs 10 fps) are quite a bit less than the 7D Mk II. The 7D Mk II is equipped with Dual Pixel CMOS AF technology and can take excellent videos, especially when paired with the STM lenses.
The big difference is the EOS-7D Mk II has a much bigger buffer (31 vs 16 RAW) and better AF system (65 vs 11 AF cross-type points). This will be crucial when one is primarily interested in sports and wildlife action photography. On the other hand, the EOS-6D is a good choice and value for those who would like to get into more serious landscape photography. For my money, I would look into a good used EOS-5D Mk III camera first before buying a new EOS-6D. You can see my works on MichaelDanielHo.com