Looking at DXO, (my new friend) the Sigma Art 50mm F/1.4 comes up as the sharpest of all the lens' for the D700. The Nikon 85mm F/1.8G seems to be the best in class and not overly expensive (especially used).
The Sigma 50mm and 35mm appear to be brilliant though! Have to keep out on the lookout. Looking at the comparison between it and my super cheap 50mm is pretty staggering
From what I have heard Tamron has some fantastic lens' and some not so fantastic ones. They do a 90mm Macro which is brilliant but I must admit that they also have a lot that aren't so crash hot.