Though the OP has not responded but I will utilize this tea break for ranting a bit :-
I am writing from memory, a weak memory at that because I simply can't remember which particular model is what , so let us paint with a broad brush. The two contenders being the 7XXX and 5XXX series. I have seen a lot of guys entering Nikon the 5XXX way and in few months time either moving to 7XXX series or go somewhere else. If I think a bit with my muddled mind , please pardon me for saying so, Nikon is perhaps using the 5XXX series as the consumer baiter , high megapixel, Light ( rather less mass hence more prone to shake), dinky little flipping LCD, a dark as my future kind of excuse of a viewfinder but WIFI checked, GPS checked blah blah.
The 7XXX series is targeted more towards the "photographers" among us , ability to use old AFD lenses retaining autofocus ( get 50 1.4.AFD save 10k, get 85 1.4 AFD and save ooops a cool 50K , get an old 80-200 f2.8 afd and buy a bike with the savings ), ability to use flash in commander mode , dedicated buttons for wb, iso , etc etc ( the buttons that are supposed to be used more ) , dual card slot ( a virtual life saver) , top LCD and U1,U2 menu banks ,better body , almost a FF like view finder, better buffer if you need for wild life . The 7XXX series brings a lot to the table.
In my opinion image quality is much more dependent upon lens and the skill of the photographer ( both shooting and PP). The body stays in between the lens and the photographer's eyes and facilitates the capture. I would not ask much help from the body , I would rather ask it not to come between an image and me. In that sense I always find the D5XXX bodies to be quite limiting. But YMMV