It really depends on what you and your friends prefer to play, honestly. If you guys really love fps games, Overwatch or Call of Duty/Battlefield would be right up your ally. If you prefer strategy games like RTS's, maybe Starcraft. I'd honestly pick a game that you and your friends currently love playing. If you and your squad are playing a game you all enjoy, the content you capture will be of a higher quality, much more enjoyable, and will feel more organic to not only you, but your friends and viewers as well.