Have you looked at the Sigma 85mm f/1.4 and compared that to the Nikon? From my Canon experiences, it's better than the 85mm f/1.2L (Focuses faster, sharper at f/1.4). I am really happy with the lens, and it produces some really nice bokeh. Not trying to gum up your decision making, just suggesting other options! Here, I'll post a few photos showcasing how the bokeh is rendered. Most of them are f/1.4 or f/2, all shot on a FX camera.
I do not agree that the Sigma has better bokeh that the older 85mm 1.4 AF-D, for the simple reason that the Sigma seems to produce strong cat's eye rendering on bright OOF specular highlights that are off-center, as well as tending toward "swirling" bokeh on the background planes. I think the Sigma suffers from some mechanical vignetting that causes the OOF specular highlights to appear football-shaped off-center, AKA the "cat's eye" bokeh shape. Take this shot of the young woman on the bench with a camera: see the background underneath the bench and off to the sides of the bench, and how the OOF highlights almost seem to be forming a "circle" across the entire background??? Same thing at the top, in the woods behind her--there is a faint "circular, swirling" rendering of the background...along with the ellipsoidal OOF highlights visible on the top left corner...neither to me are pleasing characteristics. The Canon 85/1.2-L suffers from the same effects...
This is where the Nikkor 85 1.4 AF-D is a better lens in terms of bokeh...it does not have the "swirling", circular rendering of the background planes, which is a characteristic that many old, crappy East German lenses used to suffer from. The Sigma 85mm does create a very strong
visual impression on the images, and it does have a strong, pronounced what is called a "bokeh
signature", but I'm not sold on the signature as being pleasant, compared to say the Nikon 85mm and 105mm AF-D lenses, which have a very,very,very different way of rendering the background planes and the OOF highlights. It looks to me like Sigma was CLEARLY emulating the Canon 85 1.2-L's bokeh signature, and not the Nikon look, which is quite,quite different. After all, specialty lenses from Sigma/Tamron are often aimed right at individual, very expensive camera maker lens models.