Okay, to be serious though - the game doesn't matter. At least, for those who intend to be on YouTube for long. It can be a great way to catch some search traffic, but the game is secondary (there are some rare exceptions, but as gaming preferences change, focusing on a particular game won't be sustainable).
What makes a gaming channel fantastic is the individual playing - the entertainment comes from their narration and their personality. YouTube is a personality-based medium, regardless of the content produced. For example, take a look at the Pong sketches from the first season of Saturday Night Live.
Or better yet, watch
count_teribil's videos.