Earlier quoted context omitted.
I've gone through many incarnations of HTPC's, plus tried with SageTV, Roku[1], Chromecasts, and several others... and can absolutely recommend the Nvidia Shield. It has a good 10-foot interface via Android TV (as opposed to regular Android), is kept updated, is a Google Cast target, has official apps for all the major streaming platforms, can run Plex and Kodi (for local content), and it's also possible to sideload…
That's awesome. I used to be a big fan of Sage, before they sold out / shut down. Even did the direct capture from cable boxes. I've been planning to get a Shield TV, so good to see these endorsements!
Shortly after Sage was shut down my cable company started encrypting all their channels, rendering most of my PVR setup pointless. After chasing issues with Youtube breaking API changes, I finally and begrudgingly pulled the plug on Sage. Several HTPC iterations later I feel like only now (with the Shield + Plex) do I have a comparable setup.
I did briefly play with Plex PVR with my HDHomerun and an OTA antenna, but I don't get enough channels for it to be worthwhile, and never even bothered re-installing the antenna after my roof was re-shingled last year.