Hi, lots to consider here. What level computer expertise do you have? In the past 15-years I have gone through two analog systems, one IP system, and now cloud (Ring). Oh the money I spent on AD converters.
If you have decent IP cams (3MP or above) you will need some beefy CPU to encode the video. I have tried a couple different (Mac) programs for NVR (Network Video Recorders) and they were ok but required a lot of fiddling. I also have a dedicated NVR that works great and requires less fiddling, but it was not cheap. I can push to NAS or cloud but since I have 4TB it’s not really necessary. I typically discourage $299 NVR’s because they are Chinese fly-by-night packages, they kinda work for a bit but are basically disposable.
The big issue with cloud is privacy. If you’re not comfortable with AWS hoovering all your data then avoid it and stick with a computer or appliance. Despite scary headlines, I really do not worry about it and have Ring cams on the front and back of my house. It is just too easy and it works very well. I keep four other 5MP IP Cams on the dedicated NVR and get about 30-days/TB. It is really difficult to chop down the motion activity around my house with kids, dogs, and other critters 24/7.