I don't think the key is what you record, I think it's how you present it and what you're presenting. That's why there are so many Minecraft YouTubers, but so few of them are highly popular (by comparison).
Videogamedunkey and gbay99 are both popular YouTubers (mostly) known for League of Legends content, but were both able to find success by having different styles of videos. Dunkey, for the most part, recorded post commentary for the sake of humor and never took himself too seriously. Gbay, on the other hand, is known for being able to discuss various topics at length over the course of the games that he's played, which made for videos that were interesting to watch for the duality of watching the key gameplay moments and listening to his thoughts, which sounded relatively consistent.
So the best advice, I think, if you're going to pick one game to go with, would be one that has a large following that you can use to get people watching while also offering them something new to watch.