Depending on what your lens investment is, another consideration might be the upcoming Sony A9 - the specs look amazing (including a spectacular image stabilization system). I actually like the 24-70 Sony Zeiss f4 on an A7r substantially better than the 24-70 f2.8 Nikkor on a D800e (never tried a D810). It's a newer system, without the lens choices of Nikon, but Sony has been very aggressive of late - I expect the ~50 MP A9 with world-class stabilization will be priced right around the D810, but haven't seen any real pricing on the (January release) Sony. If you have long Nikon AF-S VR telephotos, the Sony is probably cost-prohibitive (there's no adapter that preserves fast AF, and Sony doesn't have a good selection of long glass even if switching were affordable), but if your lens investment is more modest, I wouldn't buy anything at the top end until we see how aggressive a game Mr. Sony plays.
Dan