Mac Mini. Small, quiet, powerful enough to drive 4k\5k monitors and Kodi works well on macOS.
Or, if you already have a Mac running Kodi, you can airplay to an AppleTV. There is even an iOS remote app Sybu Kodi that can be used to select content, pause\resume, etc. You just have to start the Kodi app and Airplay n your Mac before you sit down in front of the tube.