I use blueiris which barely works because I'm overloading it with 9 reolinks at 4k. I'd like to figure out my bottleneck but it works enough barely that it's not worth mucking with it.
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.