I have a 4TB Hard Drive attached to an OpenWRT router (Rasberry Pi's are also a popular choice). The router exposes a locked down SSH port (SFTP only) through a cheap $5 a month VPS.
I also use Jottacloud [1] who provide unlimited (yes unlimited) storage for 7.5 EUR a month. Based in Norway, they keep an up to date warrant canary.
Client side, I backup to both of these services using Duplicati [2] which offers client side encryption, block level deduplication and excellent integration with Jottacloud and SFTP. For synchronisation, I use Syncthing [3] since I don't want to expose plaintext documents to Jottacloud. All in all, I'm very pleased and it has required no maintainence since I set it up a year ago.
[1] https://www.jottacloud.com/en/