The HTC Vive, the Oculus Rift, the Razer OSVR, and the Pimax 4K:
Notice one key difference between those other VR headsets and the PSVR?
All those other headsets are like ski goggles, pressing against your face. In fact, they all have those elastic straps that quite literally and explicitly press the visor against your face. And this is not just theoretical. Many reviews point out how using the headsets for long periods of time will leave press marks on your face (like a "wolverine mask"), and may become uncomfortable after long periods of time. Another common complaint is that it can press against your nose, causing pain in the long run.
Contrast that with the PSVR. Rather than being like a ski goggle, it's like a headband, like a helmet, that you wear on your head, and the visor hangs freely from the headband, rather than pressing against your face with force. The frontal part of the headset's weight presses against your forehead, on a rather large surface, rather than a narrow rim around your eyes.
While I have not yet got the opportunity to try these headsets, I have the strong feeling that the PSVR would be the most comfortable in the long run because of this design.
For some reason it seems that only Sony figured out this ingenious design. None of the other manufacturers did, nor have. And they aren't even trying to copy Sony's idea. (And, in fact, the four examples I listed are not the only ones. There are tons of cheap knockoffs, and a couple of a bit more serious attempts... all of them using the ski goggle design that presses against your face with elastic straps.)