If you want to try the ergonomic of α7C, check a display unit of α6600 or the latest α6700. It shares the same battery with α7C and pretty much the same grip. The grip on α7C is said to be deeper than α7III (thus easier to hold). Both α7III and α7C are good enough for some certain production level in videography, yet α7C doesn’t have the 29 min limit of recording which is somewhat more attractive if you plan to make long video rolls. α7C is said to have a better LCD in terms of color accuracy α7III (owning α7III for a long while, I can honestly say that its LCD is horrible in terms of color accuracy, you will have to struggle a while to get used to with it). In terms of autofocus, α7C is better than α7III with all updated algorithms. α7C has some downsides in photography field in comparison to α7III, that are: maximum shutter speed is only at 1/4000s (you may need ND filter in daylight shoot), one SD slot. Apart from that, they’re very similar to each other (same sensor, same imaging signal processor, same low light performance, etc.). The ergonomic is more about personal preference. Me personally I used to be a DSLR user, so I always prefer the bigger body variants of α7 family than the α7C series, since the position of EVF is more natural and handling with medium to large lenses are much more balanced. But other users may find it’s comfortable to hold a small camera body like α7C and the α6000s family. At this moment, I think it would be nearly impossible to find a brand-new, unused α7III unit so you will have to stick with used one if you choose 7III. If you don’t have any experience with purchasing used camera gears, then it’s safer to get a new α7C unit. In my opinion, α7C is not overally a better camera than α7III, it’s just a different series with pros and cons and it’s up to users preferences. Some may find this more suitable and other may find the reverse 😉. More on reddit.com

The a7c is better for video. Recommending a lens is a bit harder. What are you planning on shooting? More on reddit.com

The A7c is a more modern camera than the A7iii - it has realtime tracking AF and video EyeAF, both of which are huge improvements for street/family shooting. It's also meaningfully smaller/lighter for throwing in your travel day bag/nappy bag. If you're looking at the Sony 24/40/50 G lenses ... More on dpreview.com

Some thoughts: Identical sensor. More buttons on the A7iii, although IMHO one doesn't need them as much on the A7c. AF in the A7c is uncanny and feels like cheating at times, although the A7iii's no slouch either. EVF bigger on the A7iii, but the flippy screen in the A7c is more useful. Bigger lenses feel a lot more at home on the iii. I'd go with the one that feels better to you in your hands. More on reddit.com