Originally posted by timb64 I mainly shoot landscape/wildlife and have very little interest in action photography or video.
Worth noting that the KP, with it's accelerator chip, has evaporated one of the key advantage of a full-frame sensor over APS-C: clean high ISO capability. KP performs at same level as D750/6D in that department, which can open up a lot of possibilities with wildlife photography. Plus KP has pixel-shift, which many have found can make a noticeable difference to landscape.
D750 is a nice camera, even the cheaper D610 is fine, but you will need a new lens lineup if you go down the Nikon path, which will certainly push your whole package well over $1000. But at least there is a big used Nikon market out there, which means there may be many options for you to get some good deals on Nikon gear.