The Last of Us Part II is my favorite video game of all time, so obviously that's my top pick. (Sorry haters!) A more complete list of my top faves originally released on the PS4, and sticking with AAA selections here (as is, I think, the spirit of this thread), looks like this:
1. The Last of Us Part II
2. NieR: Automata
3. Death Stranding
4. Hellblade: Senua's Sacrifice
5. The Last Guardian
6. God of War
7. Uncharted 4: A Thief's End and Uncharted: The Lost Legacy
8. Persona 5
When it comes to first-party releases, the Sony brand is usually my favorite just in general. Their games have the feels. Usually anyway. A variation on this list expanded to include indie titles not falling into the AAA category though would definitely see What Remains of Edith Finch take the second spot and Bloodstained: Ritual of the Night would rank in well too since the PS4 version was definitely the best one at the time of launch.