Apple TV is great and all, but it's pretty useless if you want to enjoy 4K content. This is where Roku's new Ultra set-top comes in. The Ultra not only supports playback of 4K content from your favorite services, but also supports it at up 60 fps and is HDR compatible for deep color reproduction.
As for content, you get the full suite of streaming apps and everything can be controlled via an iOS or Android-powered device. Other features include 802.11ac MIMO dual-band wireless, 720/1080p upscaling to 4K, Dolby Audio with optical out, and a USB port for local playback.