I only don't have an X1 so i'll go with it.
Having been around the same time as PS4 and being less powerful, the X1 had at launch and still has a more compelling software library than it's main rival, even now months from it's launch.
I need to be clear and say that i don't care for any of the titles, both from PS4 and X1 and i only got a PS4 this early just to play the best version of MGSV:GZ, but the X1 library is still more interesting. Combined with a few japanese exclusives like Cave shooters in the future and i'm sure to eventually buy one.
I also have to say that no matter how mad i was on it's reveal, the turnaround was really impressive.