I actually tested the graphics and gameplay form the PS4 versions of the game I own.
MLB16/17 Do definately look better than 25. The gameplay is so much better too. The ball just jumps off the bat.
But the best looking MLB THE SHOW game from the PS4 era is no Doubt MLB THE SHOW 20. The graphics are so virbrant and colorful in this game. The lighting is top notch. The presentation is incredible. The gameply in 16/17 I think are better because the hitting in 20 is sort of dummed down since the ball sort of dies after leaving the bat where in 16/17 it just reacts like a real baseball.
MLBTS 25 doesn't even come close to the graphics of MLBTS 20.