PC is better. I originally got it on PS4 for the physical extras and thinking that W3 would be really intensive to run even on my new PC because its seems they always are on release but then decided to trade it in and get it on PC not long after. I'm glad I did. The PC version looks and performs better. At least at release time I could tell the PS4 version's fps were capped at 30fps or near it.(I don't care what the detractors say this boy can SEE a difference between 30fps and higher)
I'm running it at Ultra and High settings, vertical sync, 60fps capped, post processing affects save for the weird blurry effects and HBAO+ and get buttery smooth fps most of the time. Sometimes my fps takes a dump in certain swamp like areas or out of nowhere but its still playable and its sporadic. Looks and plays better on PC. Plus I'm running a few simple tweak mods that fix things that were bothering me and other folks.
I've seen videos where people were even running the game on bare bone settings and edited config inis to be able to play it on dinosaur machines and successfully did so.
Very good game and engine and as optimized as you could hope for especially in this day and age of proliferate, pitiful console ports. They did a good job.