I'd agree with the 7AC, but the 7AC II/ 7AC R are generally the same sensor/AF as the IV/ RV models, but a slightly smaller case. And unfortunately, they won't fit in the older A7C housing. The biggest difference may be the strobe sync speed as I don't think the A7C II/ R inherited the 1/250 speed of the A7s.
Another transplant from WetPixel primarily diving Puget Sound and Seattle area of Pacific Northwest. Been shooting Sony for last 10 years and primarily dive CCR these days.