Ironically,
I'm one of the few that have Witcher 3 for both, the PC and PS4... My first playthrough was on the PS4 and will say besides a few framerate hiccups at certain areas and the longer loading times for almost everything (convos, loading the zones, etc..) it was still a very enjoyable experience. I never found the game unplayable as some others have stated, but naturally people are entitled to their opinions. I also found it stellar to play that on my nice 55 inch Samsung TV, with my home theater surround sound hook-up I have rather than my nice (but smaller, heh) 27 Inch ultra HD monitor and 5.1 Surround Logitech Speakers (which still great, but not as good as my home theater set-up.)
As for my 2nd playthrough, which is going much much slower, is on the PC, and overall the visuals are indeed a pleasing upgrade, plus the Load Times are much faster (I have a GTX 980 and decent I7 Core and Witcher 3 is on my SSD drive, so I can play the game at near max settings..) However, as others have stated you will find yourself eventually using a controller, the gameplay just feels like it was built for a controller, and I can't get use to the PC Controls even after trying to rebind certain keys to more accessible areas on my keyboard. (something I still feel they went totally backwards on compared to how the Keybinds were in Witcher 2, which is perfectly fine)
So overall either decision you make you are still going to enjoy the game, if you are however unsure tech issues, than perhaps the Ps4 version may be the route to go.
Consoles have better gaming experience than PC, i own good PC and PS4 but playing on PC just doesnt feel the best way to play it.