I use a few different NAS drives to backup important files and stream media.
To backup media and stream it to my Roku, I have a
ZyXel NAS 320 with a pair of 3TB WD Red drives. I probably should have gone with a RAID setup but I've never set that up so went the easy route. Drive 1 stores all of my backups and streams. Every night a job runs on the NAS to synch up the folders to drive 2.
My wife's work files are backed up in real time to a 3TB WD MyCloud. Every night that NAS drive backs up to a 4TB WD Elements drive attached to the USB port. Nightly, her work files are backed up 3TB WD MyBook USB drive attached to the Asus router. Weekly her files are backed up to a Buffalo LinkStation with a 3TB WD Red drive located at a family member's house about 15 miles from here. I use dynamic DNS from DYN.com to communicate to that NAS via FTP.
I also have an older Buffalo LinkStation and a Hawking NAS that I need to put back into rotation when I get a chance.
We looked at the cloud storage options but they would throttle down the uploads at a certain point. We calculated that it would take about a month to load just her data to Carbonite. If she needed it then it would take just as long to repopulate a new drive. That was not acceptable if there was a project deadline. Monthly, I clone her laptop's drive via a USB to 2.5" SATA adapter so that if her working drive fails, I can have her up and running in 30 minutes. I can restore backups over the network in under an hour.
I use a combination of both Western Digital and Acronis backup software.