I went the MythTV route using the Mythbuntu distribution.
I bought a little fanless PC (four core 1.6GHz AMD powered, 4 GB memory, HDMI output - 18W peak consumption). Built in 1.5TB 2.5" low power drive for recordings. 4TB USB3 HD for stored movies, shows, music and photos. HDHomerun tuner (2 transport, 4 channel) tuner - bought a 2nd later to allow multiple live TV users concurrent with multiple recordings.
Setting up the MythTV backend takes a bit of practice but once done works fine.
The PC also provides the main frontend.
Both MythTV provides a web interface to allow remote control of all aspects of recordings, show archiving, etc.
For slave TVs in other rooms, I use Raspberry PI3 boxes running Mythfrontend (or OSMC (kodi)) with the PC set as the backend - 1080 HD only, no 4k possiblewith Pi3. Cheap, reliable, WiFi or Ethernet built in and easily duplicated to as many rooms as you wish.
Thus far I have experimented with MythTV, PLEX, OSMC + TVHeadend; all systems have pros and cons - for our specific needs, MythTV front and back seem to give the best results...
TVHeadend as a backend is slightly easier to set up and the remote web interface is a bit more comprehensive in that it also provides backend setup pages; I set up a system for my son in law using a Pi3 and HDHomerun (<£200 total cost with 3TB storage) as both backend and frontend (OSMC with TVheadend)
PLEX is great as a media source system but the DVR is still rudimentary and it costs money...
Let me know if you need to know more.