Games will be the deciding factor, exclusive ones. As yet, that hasn't been enough to get any victories for MS even with net pricing that is lower than PS4 (eg : XB1 @ $449 w/Titanfall = $390 console, free kinect, $60 game).
E3 should be interesting. I have a sneaking feeling that Microsoft doesn't have any surprises ready for 2014, but 2015 could start heating up. Whereas Sony played it pretty tight last E3.







