I don't know shit about NAS but I otherwise have solid network knowledge. My employer has been using a 2-bay NAS with 1TB of storage and it's as old as time. They asked me to figure out a good replacement for them that does all the typical reliability and security shit. They haven't really got a chance to sit down with me and tell me exactly what their needs are but here's what I know so far:
They will almost never have multiple users accessing it at exactly the same time.
They will rarely access it outside of the office, so paying an off-site service isn't really good for us.
Client confidentiality is actually important, so stuff needs to be locked up like a motherfucker.
I'm on Linux all the time but the other workers are all accessing the shared storage from Windows.
This is no start-up; They have money to burn.
tl;dr encryption and full backups are a must. Where do I even start with these? While I wasn't looking, NASs seem to have become smart as fuck. About 8TB plus any additional storage for the backups will keep us happy for a while.