Just found this thread. Like someone mentioned, the compact nature of the a7C II really dictates what feels good to use for a long shoot. Ive been very satisfied with some of the more affordable third-party glass lately. They really closed the gap with Sony.

• Viltrox AF 85mm f/1.8 II FE is a solid pick if you want to save money over the Sony version. The autofocus is reliable enough for eye-tracking and the rendering is quite smooth. Its been my go-to recommendation for people on a budget.
• Sigma 65mm f/2 DG DN Contemporary is another one to look at. Its part of their I-series, so the build quality is top-tier metal. The 65mm focal length is unique but actually works well for upper-body shots without needing to stand too far back.
• Samyang AF 45mm f/1.8 FE works wonders for environmental portraits. Its so light you wont even notice it on the camera. I usually check the comparison charts on sites like Sony Alpha Blog before buying anything. They have a massive ranking list for almost every E-mount lens which helps narrow down the sharpness vs price ratio.

The Sony FE 85mm f/1.8 is arguably the best value portrait lens for your a7C II. At around $550-600, it delivers excellent sharpness, beautiful bokeh, and fast autofocus in a relatively compact package. The 85mm focal length is ideal for portraits, and f/1.8 provides plenty of background separation.

Like someone mentioned, the 85mm focal length is usually the go-to for portraits, but honestly I've gotta disagree a bit when it comes to the a7C II. In my experience, those longer lenses make the small body feel really front-heavy after an hour or two. I've tried many setups over the years and for reliability and balance, I think these are better picks:

• Sony Zeiss Sonnar T* FE 55mm f/1.8 ZA

This lens is an absolute classic. Its tiny, the AF is lightning fast, and it has that Zeiss look that cheaper lenses just dont replicate. Its been my most reliable lens for years.

• Sony FE 50mm f/2.5 G

If you want the best build quality to match the a7C II, this is it. Its way more rugged than the Samyang or Viltrox options. Its very sharp even wide open and actually fits in a jacket pocket. The 85mm is fine for tight headshots, but these shorter primes are much more versatile for portraits... especially if you want to keep the kit light.

^ This. Also, if you want something even more compact to match the a7C II vibe, Ive found a couple of third-party gems over the years that punch way above their weight. I used to carry heavy G-Master glass, but it felt so unbalanced on the smaller bodies that I started looking for lighter alternatives.

• Samyang AF 75mm f1.8 FE is tiny. Seriously, it weighs next to nothing and the rendering is surprisingly creamy for the price.
• Sigma 90mm f2.8 DG DN Contemporary is another one. The build quality is pure metal and it fits the a7C II aesthetic perfectly, even if f/2.8 sounds slow to some... honestly, its sharp as a tack.
• Sigma 65mm f2 DG DN Contemporary is my sleeper pick. Its a weird focal length but amazing for environmental portraits where an 85mm feels too tight. That Sony 85mm is definitely the safe bet, but these smaller ones really make the camera feel like a kit you actually want to carry all day without your wrist hurting after an hour. Ngl, I use the 65mm more than almost anything else lately because the bokeh is just so smooth.