Well, I stand corrected regarding the sheer number of Amazon's channels. I'd point out though that Amazon is missing some real heavy-weights. For example, there is no Ultraviolet provider like Vudu or Flixster on the Fire TV. That alone makes the Roku more versatile. There is also a plethora of private channels for Roku which are probably not included in their official count.Roku claims 1700 channels and Amazon claims over 3000, I could not find a good source for android tv. If Apple does not best both of those number in 6 months I would be shocked.
And I wouldn't be surprised if the Apple TV didn't get either Amazon Video or Vudu anytime soon ...