Stardew Valley is an extremely charming, polished, and nuanced game that is a breath of fresh air in the management game genre and the entire games industry as a whole. I don't think I've had so much stress-free fun in a game for years, and would highly recommend it to anyone.
Sword Art Online: Lost Song is a great sequel to its predecessor Hollow Fragment and introduces a plethora of new and interesting mechanics. However, the majority of these mechanics like spells and healing are put in the backburner in the singleplayer story, and are only ever viable in multiplayer mode.
Disgaea 5: Alliance of Vengeance is an absurdly deep game is definitively the go-to SRPG experience on PS4. It has the whole package – great art, superb music, hilarious story, deep and complex mechanics, and a post-game that will keep you playing for hundreds of hours.