While I am very happy with the Apple TV 4 (and Roku a close second), the NVIDIA Shield Android TV box might be something that I pick up in the future. According to the folks at Plex, the NVIDIA Shield has received a firmware update that will enables it to act as a Plex Server. If you aren't familiar with Plex, Casey Liss provides an overview on his blog.

While I currently have a Mac mini powering my Plex server, if it ever dies, I will likely replace it with the Nvidia Shield. According to information I found, you can easy run it headless and access your Plex server management from the built in web server.

You can pick one up with 500 GB included on Amazon for $299.