I’ve been pretty pleased with my 2020 iMac 27 — the one with the upgraded webcam among other enhancements. I have the base model, which is fine for my office-type uses. And I’ve been pretty pleased with it. But I was able to see it and the iMac 24 side by side in an Apple Store (my local one surprisingly still has a 27 on display), and I thought the webcam on the 24 was quite a lot better — the difference was greater than I’d expected. I’m a heavy Zoom user for work, usually as the host. Is it worth replacing the 27 just for that? Not sure. But if buying now, I would go with the 24 (not that the 27 is going to be an option for much longer). With the disappointing Studio Display webcam reviews, it does seem to be the best option for desktop video conferencing.