Roku has finally surpassed Apple TV in terms of popularity in the US. "The Evolving Market For Streaming Media Devices," by market research firm Parks Associates revealed that "44 percent of households that own at least one streaming device use a Roku," while Apple's avowed hobby, the Apple TV, accounts for "26 per cent of both sales and usage." Both the latest Roku and Apple TV sell for about the same price although there are various Roku models featuring lower prices and limited features.
While not acatually in the same league, Google's Chromecast has been making waves. Being a much cheaper (and functionally limited device) may have added to its popularity. Google and Roku sold an estimated 3.8 million streaming media devices last year, with Apple selling just over 2 million Apple TVs.
While Apple has pushed modest updates to Apple TV in the US (more limited in Canada) and includes various new services, Roku's business model is to offer as much free content as possible as well as integrate the ability to play casual games with their wireless controller. Many believe that Apple TV is up for a redesign and a feature upgrade, perhaps in tandem with the upcoming iOS 8 release in the fall which could change the game in streaming media device market.
Source: Appleinsider