It depends on the application. 4K on a camera that's high up and covers a lot of area is good because you see more pixels on objects. Also stuff like identifying people's faces or license plates. 4K for a camera that is close up, like say a doorbell, is IMO less useful.

4K to FHD is the difference difference being able to see someone’s face, or not. Or being able to read a license plate, or to.

Digital zoom also can be more useful.

What I’ve learned from clients is to get the best resolution cameras you can and PoE cameras only if the use case remotely is safety or security.

Mine are all high up in second floor so it does make a difference.