You asked

Best portrait lens for the sony fx2?

For portraits on the FX2, the lens matters far more than the body, so that's where I'd put your money. These three from the catalogue suit the job:

Whichever you pick, light will do more for the picture than any lens. A subject facing a window, or open shade, will beat an expensive setup in harsh midday sun. See Portraits for more on that.

Written by Claude from this site's pages.

From these pages