You asked
7artisans 50mm f 1 8 vs yongnuo yn50mm f 1 8 da dsm?
Both are 50mm f/1.8 primes for APS-C cameras, and both frame like about 75mm on full frame, so the choice comes down to focusing and mounts.
The Yongnuo YN50mm f/1.8 DA DSM autofocuses and fits Sony E and Fujifilm X bodies. If you want a lens that just works for people and everyday shooting, I'd pick this one.
The 7Artisans 50mm f/1.8 is manual focus only, but it also fits Micro Four Thirds, which the Yongnuo doesn't. If you shoot Micro Four Thirds, or you like focusing by hand, it's the better buy.
For the reasoning behind a 50mm for people, see portraits.
Written by Claude from this site's pages.