What is the best device for watching internet content on a TV?
There isn't a single best device.
In my opinion, the competition comes down to Apple TV and Roku.
Benefits of Apple TV:
- Native YouTube channel, which Roku does not have.
- Focus on user interface and creating excellent user experience (eg, Netflix is better on Apple TV than on Roku).
- Tight integration with iTunes Store, with iTunes library on a Mac, with iTunes Home Sharing and with iTunes Match.
- Screen Sharing with a Mac in OS X Mountain Lion; use as an external monitor for a Mac in OS X Mavericks.
- Use as an AirPlay receiver.
Benefits of Roku:
- More channels. Practically unlimited channels, in fact.
- Plex channel (and other stuff that can be added on top of Plex), which Apple TV does not have. Note: Running Plex media server on a computer and streaming movies to the Roku is a thousand times better than doing the same on iTunes.
- Amazon Instant Video channel, which Apple TV does not have.
I have an Apple TV 3 and a Roku 2 XS, and the two most frequent services I use are Netflix on ATV3 and Plex on R2XS. With a universal remote control, switching between them is so easy that I hardly notice they're different boxes.
For someone with a new-ish Mac that will be running Mavericks, I think Apple TV will be a must-have.
For someone who downloads a lot of legal DRM-free movies and television programs and wants to watch them in the living room on the big television set, Roku with Plex is a must-have.