I am in the same boat as you, but I went for Battlefield. I hear the multiplayer, when working as intended, is the best. Only problem is the many bugs in the game currently, they released a patch yesterday, but it hasn't fixed much. If you can put up with the problems of being disconnected from matches sometimes, until the game is fixed properly, I say go for that game. Some modes are working fine, such as team death match.
I was thinking about Killzone, but the reviews were kinda poor, saying the multiplayer is decent, but not as good as Battlefield 4, and the single player campaign runs out of steam about half way through the game. I will wait for a price drop on that game. Fifa...I don't play them games so have no opinion on it. But if you want a game to show off you PS4, then Battlefield or Killzone are probably the best lookers. I just hope the 64 player conquest matches are fixed on Battlefield , will be awesome when it's sorted.