3rd party attempts at Time Machine compatibility have not gone well in my experience. Most NASes implement it by taking what Netatalk/NetAFP releases, and it will likely corrupt the backup after a few months. I have my Macs set up to backup to a ReadyNAS, and an Airport Extreme with a USB disk attached. The NAS backup is rebuilt from scratch every few months, the Airport one ran fine long enough for my machines to start expiring old backups.

Offsite, I use Backblaze. It's on my desktop (Mac Pro) and laptop. I cloned all my old data off the NAS onto a 4TB drive sitting in the Mac Pro, so it's all backed up that way. This is only a transitional strategy, while I can leverage OS X Spotlight and other tools to whittle down the crap I'm still keeping around. I trust Backblaze to work fine on OS X, as their company has a number of ex Apple engineers on staff.

The two NASes I have at this point are turning into a way to get rid of my DVD shelves. Plex is part of this mix, and I've started just exporting my DVDs as a flat .MP4 files. I don't run the Plex server on the NAS directly, as it's transcoding power is underwhelming. Going to rethink this soon though, as the new Apple TV is coming and will be the point where the Mac Mini leaves my TV.

Ideally if I were to redo anything today, I'd seek out a solution that runs a file system that can detect and possibly stop bitrot, and allows spotlight searches to work. I've been tempted to just turn the existing NAS into a iSCSI box, and let my Mini run as a ZFS server. But I've not gotten around to this, and hope that Mac filesystems improve before I do revisit this likely in 2018. Been watching Marco Arment's progress in this arena. One handy thing for him, Backblaze backs up his entire NAS due to his use of iSCSI.