Indeed, Apple TV trails Roku and Google for most-used streaming devices, according to research firm Parks Associates, while it is almost neck and neck with Amazon's Fire devices. By offering lower-priced, basic models such as the Fire Stick, Roku and Amazon have been able to rapidly meet and surpass Apple's market share, said Barbara Kraus, director of research at Parks Associates.

While the lower-end sticks and more powerful cube models each take about half the market now, Kraus predicted that by 2019 sales of lower-cost stick streaming devices, like Google's Chromecast, would grow faster than the more-powerful cubes, like Apple TV and Roku 3. She predicts the low-cost alternative will be two-thirds of the OTT market in four years. 

From the article "Is Apple's TV upgrade too pricy for consumers?" by Anita Balakrishnan.