I think it's a foregone conclusion that Xbox will be the more powerful console this generation.
I think the better question is will that yield better results for Xbox in territories they are not popular in. And with Sony's hiatus on E3 actually pay off if they are ramping up first party for launch so as to not have another 2013 launch with very little first party.
I feel that If Sony and MS have their first party out in the wild it will be a more clearer picture of the landscape and see if the more powerful system trumps Sony's First party branding.