I think that most everyone here will concede that the PS4 will outsell the XB1 handily.
BUT, I think that buyers of the XB1 will be using their consoles for much longer than the PS4 owners.
It is obvious that as just a games machine, the PS4 has an advantage today. But as time goes on, with the integration of Windows 10 into the XB1, the XB1 will be a better universal games machine. M$ has clearly decided that they will open their doors to what publishers want(EA Access). Sony can sell 25-30 million PS4's by the time Windows 10 comes out next summer. By the end of 2015, there will be 50 million+ devices that run Windows 10, not including the 15 million XB1's. With the app support that comes with Windows 10, the XB1 will have access to 100,000's of apps and GAMES!
Keep in mind, developers only need to add controller support to any Windows game to make it compatible for the XB1. The cost will be minimal. 1,000's of new games for the XB1 by the end of 2015.
Like M$ keeps saying, this is a marathon not a sprint...
It is near the end of the end....