What genre of games will you be playing mostly? What genre do you feel would best represent your channel if tied into a background? That is what I would be asking myself, with your channel so far at least it looks like you like horror games, personally I would choose to make something suiting to that if thats what you will be playing mostly say like blood spatters, creepy looking things from the games you play. If not though I would go with something more generic, perhaps black and clean looking with some nice text with your channel name on it.