The topic of streaming video devices seems to keep coming up. My ability to review all the options is very limited. TomsGuide has a good overview of streaming devices they really like the Roku 3. Plex is highly recommended to maintain your home’s video library. You can use several devices (including the Roku) for accessing that library.
I like the idea of the Apple TV. But, you can’t use an (un-hacked) Apple TV to access Plex directly. Yet, I would be tempted to get an Apple TV stilll, because of the incredible usefulness of AirPlay mirroring. This allows you to work around any limitations that the AppleTV has itself, because every decent video option has an iOS app which can play content through an Apple TV. AirPlay is one of those things that Apple really got right… as long as you only use their ecosystem of devices.