According to a new eMarketer study, Roku is now the leading connected-TV device in the U.S. Roku has more users than Amazon Fire TV, Apple TV and Google Chromecast. The research firm estimates that 38.9 million U.S. consumers will use their Roku devices at least once per month this year. Chromecast will follow at 36.9 million users, Amazon Fire TV at 35.8 million, and Apple TV at 21.3 million. Roku is the only one of the four leading brands that is not connected to an affiliated content service and, as a result, has signed agreements with numerous partners.

“Roku has used its neutrality to strike deals with a wide range of partners, including smart TV makers, [over-the-top] service providers and social media companies,” said eMarketer principal video analyst Paul Verna.

“Over the next few years,” reports Variety, “Apple TV will continue to lag further behind its three rivals, eMarketer projects. One big roadblock for Apple TV is its premium pricing. The fourth-generation Apple TV devices currently start at $150, whereas Google, Amazon and Roku each sell streaming sticks priced below $40.”

EMarketer estimates that by 2021, Roku will experience a bump to 69 million monthly users, while Google Chromecast will reach 64.6 million, Amazon Fire TV will climb to 62.6 million, and Apple TV will only reach 25.2 million. These figures represent total users, not unit sales.

“One other notable estimate from eMarketer’s report is that it downwardly revised its forecast of total connected-TV viewers, due to increased sales of smart TVs,” adds TechCrunch. “This will impact those in the market for a third-party connectivity device, Verna said.”

“All told, 168.1 million U.S. consumers will watch streaming video via a connected TV device this year,” a 10 percent increase over last year, notes Variety. “Overall, smart TVs will capture the most streaming-video viewers with 81.2 million U.S. users this year, followed by game consoles with 62.8 million users. Blu-ray Disc players will have 29.0 million internet-video users in 2017.”

Roku is expected to file for an IPO this year, and will reportedly be seeking a $1 billion valuation. According to Roku, the company earned nearly $400 million in revenue last year, including earnings from its media and licensing business.