Opposite to "follow" button
Note: I do not mean "unfollow" button (that lot of users would like to be disabled or have confirmation question). I mean a button that puts a channel to some black list tab like Following / Ignored or Following / Filtered Out tab. And then Twitch would not display those channels on any other list or tab to that user.
Benefit is that lot of channels / streamers are boring or annoying to user. Tastes vary so it does not often correlate with how popular these channels are among other users. Chance to stumble upon such channels again will be lot lower that way and that perhaps makes user's experience better.