Pretty sure you'll have more potential audience with XB.... PS has already a ton of content... It'd be like trying to do the next big cat video...
Nintendo first especially if you do handheld too... XB second especially if you talk about other MS projects in relation to XB or gaming... And then PS and include vita if you do maybe a little mobile...
I'm saying that cause tags (accurate ones) help your SEO and can build up an audience... And I think MS gaming related video can have more relevant tags than PS....
but it's your show, your choice











