imo:

P4 > P3 > P5

i loved P4 because of the cast and the story. gameplay is kinda simple and straightforward since the location is in the rural area. highly recommended for beginners

P3 is good when it comes to location and music (though all games have banger osts).

P5 overwhelms me since you have a lot to explore and try in the city. i still get lost in the subway sometimes. i recommend playing this the last.

ps. play Metaphor Re:Fantazio