Maybe tryout XPEnology NAS, all it does is to allow Synologys DSM OS to run on your own hardware.

http://xpenology.me/

MikeAqua:

 

I use OneDrive too but my concern is that in the event of a ransomware attack, the files on One Drive would also be encrypted.

 

Yes, ransomware can encrypt onedrive files. I know of that happening.
Fix was easy, in Onedrive, roll everything back to a previous version.

Just as ransomware can encrypt everything accessable on a NAS.
If its not a removable device & separated from the system after backup, its not a safe backup.
Power surge : blown PC, Blown NAS . Remember , you are planning against worst case scenario.

One thing to consider (it does happen)
someone over-writes a fie or it gets corrupted. Even with incremental & rollbacks etc (versioning?), eventually all the 'good' 
backed up versions of that file will be overwritten. When you discover the issue it may be too late
So make a 3month or 6month,12 month one off complete backup , and keep it separated from daily backups.

Personally , I think multiple USB HD's are a good backup option. You have multiple separate (incremental) backups on multiple USB HD's, can easily be stored offsite, if removed after backup then its safe against hacking,ransomware,power surge etc.
I wish I went with the USB Drive option rather than the NAS I bought.

1101:

MikeAqua:

Personally , I think multiple USB HD's are a good backup option. You have multiple separate (incremental) backups on multiple USB HD's, can easily be stored offsite, if removed after backup then its safe against hacking,ransomware,power surge etc.
I wish I went with the USB Drive option rather than the NAS I bought.

The problem with USB when you have large volumes, in my case Plex media library. Multiple USB drives ceases to be viable. Currently I have 8TB.