nikkor 85 1.8 mm vs 85 1.4

The key question is: How much money do you have? IMHO, the 1.4 is slightly better than the 1.8 in the more subjective areas: for example, you can find lots of posts raving about its "dreamy" quality. On the other hand, you can find some who argue the 1.8 is better on the D800/E than the 1.4. Given the above, I didn't see enough of a difference to justify the additional cost.  (FWIW, portraits aren't my main interest.)

I am continually surprised by how good the 1.8 is, and how often it delivers (IMHO) superb results.