First I will state my PC specs. I5 2500, 16 gigs of memory, and a sapphire 7950 with 3 gigs. I compared Metro low light + crysis 3 to my PS4 running Killzone, since that's the only PS4 game I have right now other than the Playstation Plus games that are free. I have to say from what I can tell it's pretty much a wash. With my hardware anyways. I can't tell which really looks better. I can say Crysis 3 has better rain effects, but killzone looks just as good with the fire and smoke effects. Character models are about a wash. Textures look SLIGHTLY better on Crysis 3.
Killzone has more stuff going on for sure as far as animation on the screen. Killzone runs like butter, I can make my Crysis 3 run the same but would have to lower settings a little. Shadows look better on Crysis 3. Metro low light I would say has the same strengths as Crysis 3 for the post part. Lighting looks better on Killzone than Crysis 3, but about equal with Metro low light. All in all man like I said it's about a wash. To me KZ and the PC games I have look like they could be on the same hardware. My PC may have a SLIGHT edge, but man you have to look hard for it.
For a $400 PS4 to be able to completely hang with my PC is very impressive.