You asked
Samyang af 50mm f 1 4 fe vs sigma 50mm f 1 4 dg hsm art?
Both are 50mm f/1.4 autofocus primes for full frame, and neither has stabilisation. The big difference is mounts. The Samyang, the 2016 original and heavier than the II, is only made for Sony E. The Sigma 50mm f/1.4 DG HSM Art covers Canon EF, Nikon F, Sony E and L-Mount.
On a Sony E body, they frame and blur the same way, so it comes down to which one suits you. If you shoot Canon, Nikon or L-Mount, the Sigma is your choice, and it's the one I'd pick for flexibility if you might change systems. For more on third-party lenses in general, see Lenses. For a portrait lens in this range, see Portraits.
Written by Claude from this site's pages.