I quote myself from another thread:
If DxO is to be trusted, the best primes for D800E would be:
Nikon 85 f:1.8 G, 35 points, the SHARPEST lens they have measured so far (lens + camera combination, D3x). $500.
Sigma 50 f:1.4 DG, 28 points, sharpest normal lens so far. $500.
Sigma 35 f:1.4 DG, 30 points, the sharpest mid-wide so far (measured with canon 5D3, D800 should be better). $900.
Nikon 24 f:1.4 G ED, 29 points, best "landscape-wide" so far. Almost $2000.
Carl Zeiss Distagon T* 15 f:2.8, 23 points, best ultra-wide. $3000.
As we can see, the quality goes down with wider angles but prices explode, so stitching, when possible, is recommended.
Nikon 85 and those Sigmas are real winners in both quality and price. Nikon 14-28 as practically as good as 15mm Zeiss, but $1000 cheaper. It could also replace the 24mm f:1.4.