I do online backup to a cloud provider, and a monthly dump to external USB drives that I keep and rotate at my mother in law's house (off site:).
More than any technical advice, I'd strongly urge you to check and understand honestly whether you're looking for "NAS" (a place to seamlessly store data) or "a project" (something to spend fun and frustrating and exciting evening and weekend time configuring, upgrading, troubleshooting, changing, re-designing, replacing, blogging, etc). Nothing wrong with either, just ensure you pick the path you actually want :->