Very cool video. Thanks for posting it James!
My thoughts:
1. The PC seems to be running it with more effects, so it looks better on PC.
2. The PS4 version still looks amazing, and considering that you'll probably need a PC with 2 Titan GFX cards to pull off that demo, I think the PS4 version wins?
Either way, as someone that's always been a graphics/eye-candy whore, I am SO excited about this new tech. I feel very blessed to be living in this day and age - games using the Unreal 4 engine are going to be jaw-droppingly realistic.