I’ve been using a Synology NAS for a few years and I know LTS so too for certain projects. They’re great little boxes, easy to configure and once done, bar the usual updates, leave and forget. Personally I’d recommend one with an x86 processor as that gives a bit more flexibility in terms of running extra things such as Docker containers. Of course if your requirements are as simple as you stated that may be overkill.
QNAP make some good NAS storage boxes that are very good and they are maybe a bit easier than Synology navigating the admin interface. I would check them out. Either brand will be fine and price is about the same between the two.
I second Synology and Qnap. They’re very similar. Both have a wide range of offerings for every budget, and both have plenty of info available on them on the web.
For 4-8 TB for home use, with only network file sharing as a prerequisite, a simple 1 bay unit should suffice. Get a 2 bay unit if you want redundancy, or a 4 bay unit for extra power and expandability/futureproofing. If you want to experiment a bit with the extra functionality they have, then don’t go for the lowest budget versions, as the CPU’s in them can struggle with workloads other than simple file sharing or web serving.
Both brands are capable of backing up to a number of cloud based storage providers. If you put critical data on them then it is worthwile looking into that. I personally like Backblaze as a cheap reliable option.
I’ve been using QNAPs for a couple of years now, basically they are reliable for storing files, never had any issues on that front. Mine is an 8 bay, with QNAP the number of ethernet ports / IP cam licenses vary with the bays. Pretty easy to setup with smb / FTP. The apps they have aren’t well supported so you don’t always have the latest version and the virtualisation module isn’t up to much but usable for light tasks.
However, I have noticed the prices are kinda wild I got mine for 600£ (regular price off amazon) 4/5 years ago and the similar model is now more like 950£.