For me this is a tough call to make. I have seen threads about which one will reach 10m first between Wii U and X1, but which one do you think will reach this goal first. PS4 at 10m or X1 at 5m?
I think I would say X1, it feels a bit more safe to say. But on the other hand the sales of PS4 still seems so stable at the moment that when big titles hit the market I am not so sure how much more the sales will be. Difficult to say because of hardware shortage. And the X1 will also see boosts with big titles hitting the market, by no doubt.
If they are sold at the exact same pace the X1 would however reach 5m before PS4 reaches 10m.
So, what do you think? Can the PS4 sell another 4m consoles before X1 sells 1.4?
(source of numbers: http://www.vgchartz.com/article/251540/ps4-vs-xbox-onevgchartz-gap-chartsfebruary-2014-update/ )