Apple: Apple TV ($99)
Alternative: Amazon Fire TV ($99)
We could have placed the various Roku boxes or Google's Chromecast in this mix, but it's all about the ecosystem.
The Apple kids will point to Apple TV's AirPlay function all day and blather on about integration and the wonders of your desktop and iTunes on your television. Of course, it doesn't hurt if all of your smartphone and tablet content is just in your set-top box to begin with.
Amazon's player is a thing of beauty for all of the reasons Apple supporters always mention: It has access to Amazon's cloud-based content, it's integrated with your existing Amazon account for Amazon video and movies and it has access to Amazon Prime customers' streaming libraries -- which will soon include HBO content.
That, right there, is the rub. Amazon's entertainment ecosystem has a streaming video option that may not be as vast as Netflix's, but is more than iTunes offers for a fee already built into its Amazon Prime delivery service. It also offers games, which are notably absent from the list of iTunes offerings. Lastly, and most importantly, it includes both Netflix and Pandora.
We'll note that Amazon Fire TV includes Netflix despite the fact that it's a direct competitor to its Prime streaming video service. Apple, meanwhile, stubbornly refuses to carry Pandora because of its in-house streaming music service -- iTunes Radio. Amazon realizes that giving customers something they actually want may earn you more business than ignoring your biggest competitor in favor of a not-quite-ripe competing version of their product.
Speaking of that distinct lack of ripeness....