Why? The lenses. First of all, the 6D kit with the 24-105 f/4 looks like a good deal, and the 24-105 seems like an ideal lens for walking around with a FF body. As far as I know, Nikon has no lens that really competes with the 24-105. The other main lens that I see myself getting is the 70-200 f/4 IS, which is great for someone only semi-serious like me to walk around with
Lenses! The most important part of the gear!
Never say never, but I think that I will not leave Canon unless the competitor deliver a Nikkor 70-200 F/4 "VR".
I bought a used 5D classic for less than 1000 Eur, and I hope it will last until a used 5D3 will cost more or less the same amount (in four years maybe?).
If my 5Dc crashes tomorros, I think I'll buy a used 5d2. Or a Nikon body, provided I can put my EF 70-200 F/4 L IS in its mount. I do like its sharpness, colors etc (most canon-users know what I mean).
I wonder why cigarette producers have to state that nicotine gives you dependence, whereas I didn't read the same WARNING on the box of the EF 70-200 F/4 IS when I bought it.
P.S. You can fit a Nikkor lens on a Canon body, but not vice versa.