[NIKON D4, 85.0 mm f/1.8, Mode = Manual, ISO 50, 1/60, ƒ/2.8, (35mm = 85)]
When shooting headshots/portraits I have found that when I am using a zoom lens I tend to move back and forth too much, which can distort the person’s face.
A few years ago I ran a test with my lenses to see which lens I preferred and here is that test.
Now I don’t always shoot it wide open at ƒ/1.8. Often when I get close enough to fill the frame this is too shallow.
If I back up and get a 3/4 photo of a person, then the ƒ/1.8 can work really well. You see the closer you get the shallower the depth-of-field. So, if you back up you increase that depth-of-field.
It really does well to help isolate your subject, like this couple at their wedding, but I still get a sense of mood with the background out of focus.
Now I can tell you the best thing to come along for Nikon was when they started making full-framed mirrorless cameras. I love the combination of the Nikon ƒ/1.8 and the Nikon Z6.
The Nikon Z6 has eye tracking and that really helps with getting your subjects eyes into focus.
Hopefully you will run your own test. Shoot a portrait of a person like I did with my daughter and keep the head size the same throughout in the frame, then pick your favorite lens.