I am a fan of Roku.
Primary reason is they are impartial - a search will pull up all options, not just Amazons (maybe Amazon has gotten better about this, but a friend has one of the new sticks and I noticed it was still directing me to Amazon content and I had to search harder to find what I wanted for free on NetFlix instead of having to pay for it on Amazon (I have prime, but this was not one of their free shows).
Also, I wonder if the feud between Amazon and Google over smart speakers may reach the point of excluding Google (aka YouTube) content from Amazon Fire and Amazon content from Google Chromecast.
I think the newest best Fire is a bit quicker, but the Roku is no slouch.
I also like the idea of supporting Roku as a (financially) small company which was a major force in bringing streaming to the average household rather than the corporate behemoths that are stealing our souls
! Now what did I do with my tin foil hat?