Since posting this ranking for 2015, there have been some changes in the landscape. First off, YouTube is allowing channels to hide their total view count and several channels from last year's list have obscured that count. I'm not sure why, but the remedy for 2016 is to rank the channels by subscribers.
I've also made a judgement call to remove two channels from the rankings based on content. The list below represents YouTube channels that are primarily dedicated to croquet video. Your 2016 list: