[davidmanze]

I have a hard time to find obvious differences. This gallery I mostly set up for sake of bokeh: https://sojujo.smugmug.com/Testshots/2-different-85-mm-on-Z-7/n-sBzfZt

Please note that I was rather sloppy in terms of "scientific comparison": no tripod, two different bodies with the same sensor size, two different AF systems with some "impossible" subjects for each of them (that was also interesting to me). It's mainly to compare bokeh.

   I'll go along with the Sigma producing a nicer bokeh than the Nikkor there JoJu ..... but they had to choose one of the most difficult backgrounds to expose it ........ stones, gravel and general random clutter at distances which trip up many a lens.
     The Nikkor does what is the start of bubble bokeh, with that vague circular thing starting to form.

   If I was seriously doing portraiture I would choose Sigma ...... both the 85mm and the 105mm ...... but on a ML body.

  Nevertheless, the Nikkor is a huge upgrade from the AF85mm F1.8G .... and not unsurprisingly AF85mm F1.8D.

    Just looking on line this minute the Sigma Art is available for 805 euros on promo .....