You asked
Sigma 85mm f 1 4 dg dn art vs tokina atx m 85mm f 1 8 fe?
Both are autofocus 85mm primes for full frame, neither is stabilised, and both fit Sony E cameras. The difference is aperture. The Sigma 85mm f/1.4 DG DN Art lets in more light and gives a thinner background. The Tokina atx-m 85mm f/1.8 FE is a stop slower, but it is still the classic full-frame portrait lens.
The Sigma also mounts on L-Mount, which the Tokina doesn't, so it's the safer choice if you might switch systems later.
My pick: take the Sigma if you shoot indoors, in dim light, or want the strongest blur. Take the Tokina if you mostly shoot outdoors in good light and want to keep the kit lighter. For more on why an 85mm suits portraits, see Portraits.
Written by Claude from this site's pages.