I have a 4 bay Synology NAS with 4 12TB drives set up SHR (Synology Hybrid Raid). That yields about 32TB of space with 1 drive that can fail and not lose any data.
That all gets backed up to four 18TB external drives (2 swapped out every few months, with 2 offsite drives at my office, and 2 connected to the NAS that backup the NAS nightly).
Edited video goes to YouTube as a separate extra backup.
Since I think you have more data than me, I would go with a 5 bay NAS. It's pricey when you first do it, but the peace of mind of (hopefully) not losing any data is worth it IMO. I believe with the 5 bay NAS you can start with 4 drives and either use the 5th bay to expand later, or you could also use that as a hot spare so if one drive dies it automatically re-builds to the spare.
EDIT: Recently started working for a company that does robotic tape backups (LTO). Hoping I can bring the NAS into work one day and backup everything to tape for even more security. 18TB tape costs $85, and is much more reliable than spinning discs.