You asked
Nikon z 135mm f 1 8 s plena vs nikon z mc 105mm f 2 8 vr s?
The Nikon Z 135mm f/1.8 S Plena is the one I'd pick for people. It's faster, so you get more background blur, and at 135mm on full frame it gives you tight headshots with room between you and your subject. Its trade-off is that it isn't stabilised, so keep the shutter speed up when you shoot handheld.
The Nikon Z MC 105mm f/2.8 VR S is shorter, slower and stabilised. That makes it the easier lens to hand-hold in dimmer light, and it's a more modest choice if you want a general-purpose telephoto. Both work on the full-frame Nikon Z bodies, and on APS-C they frame like about 202mm and 158mm.
If portraits are your main reason to buy, read the portrait lens guide first. You can compare the full lists in the Nikon Z mount section.
Written by Claude from this site's pages.