I had a bad experience with Swann some years ago - their app was terrible for reviewing and extraction of clips. May be better now though.
I installed a Hikvision one about 10 years ago for a client (8 cameras) and it's had only one fail in that time, and still recording happily, so they seem fairly solid - Their app is not the best though for reviewing video, and the NVR setup is still pretty old. They changed their sales pitch a few years ago and now I believe sell Hlook to retail, and in theory only sell the Hikvision to dealers and installers. Always ways round it though.
There are better systems, but if you want a good app and are on a budget, Reolink cameras are worth a look. Just installed one for a family friend (IP NVR and 4 cameras) and have a reolink camera myself, albeit recording to my own NAS software.
First thing you need to decide in any case is how long you want to record for (14 days, 28 days, etc) as that will affect your choice of hard drive, and possibly the cameras.
8MP cameras are better quality if you want number plates etc, but take more space recording.
5MP cameras are generally OK in daylight, but often not great in night vision without assistance (extra IRs or a floodlight)
These days I wouldn't think you want to go below 5MP unless its a camera where the quality makes up for the lack of pixels.
Some of the cameras have much better (colour) night vision, but they are expensive..
So it's a balance between the best cameras and the hardware to cope with the amount of throughput, and lesser cameras but with lower hardware requirements.