It all depends on if you need to transcode or not. If the video players you plan to use support all of the formats you are working with, then you can honestly get away with connecting an external hard drive to a router, and then creating a network folder for each system you want to back up, and then a additional share for media backups. I currently do this, and it forms my incremental backups. I also use my router to stream media to my various devices. It handles multiple 1080p 10 bit streams with no problem, including when a backup is taking place.
Most routers offer DLNA support, as well as smb shares, thus many devices can use them.
For my ARM based systems (tablets, smartphones, etc, I use players which support multiple formats and smb shares, such as BSplayer https://play.google.com/store/apps/details?id=com.bsplayer.bspandroid.free&hl=en
For large backups, I use my home server system. which is a cheap system (Phenom II x2 550 build and a MSI 870-G45, crappy video card, and a bunch of hard drives). It runs windows 7, and has network shared for each drive, and I have my other computers simply back up to it. It also acts as my VPN server, NVR, and game server when needed.
I use the router because the netgear readyshare vault software is really easy to use and free, and does incremental backups every 3 minutes.