I have or have had, a D7000, a D800 and a D600. The D7000 was a joy to use because of it's small size and the crop factor was nice for closeups and what little wildlife shooting I do. (mostly hummingbirds). Unfortunately I burned a hole in the shutter shooting the eclipse last June. An expensive mistake!!
The D800 has the most amazing image quality you can imagine, but there seems to be an issue with all the focus sensors being calibrated uniformly from left to right. Also it is much larger and heavier, and doesn't uste the wonderful little matchbook size $15 wireless remote, but uses a very clunky and far more expensive unit with a separate transmitter and control.
The D600 seems to have the best of both worlds, the ergonomics and cheap remote of the D7000, with the full frame advantages of the D800. I sometimes think I'll miss the extra 12 megapixels, but not yet.
BTW, my brother shoots Canon, snd there's really no "better" just what works for you.
I've also had Nikon F3HP, D70, D2X, and D90, all great in their own right.
I'm a noob here, so it's nice to find a photograhy forum in these parts. I'll be back!
PS--Do I need to become a subscriber to attach some of my photos? Thanks.