I have a Hikvision system (3 x 4k cameras + NVR) and it works ok. Quality is excellent and reliability is good. Be aware that Hikvision are trying to remove their cameras from the DIY market in the UK and make them “trade only”, so they are supposedly not available to amateur installers. I got around this by ticking “yes” to the “Are you a trade installer?” when I ordered them and no further questions were asked 🙂
Installation is very easy (if you understand networking, can drag cables around and terminate CAT5) and they were up and running in a few minutes (although the physical installation of the external mounts took *much* longer to get an entirely covert install!)
The only bit that kinda sucks is movement alerts. They are nearly impossible to setup reliably for outdoor cameras in such a way where rain, wind, sun, cats, squirrels etc. don’t set them off continually. It feels like it needs a whole step-change in sophistication of their image recognition engine before it’s actually usable.