I voted for the PC. Potentially better graphics and performance if you have all the expensive hardware to go with it. PS4 will definately still be just as impressive and right out of the box, so to speak.
But when all the dust settles and we have finished playing our third and fourth play through, those with the PC version will most likely be able to modd or at least download moddable content.
No not the little extras you pay on the side that is official, but full blown free modifications be it side quests, new player characters, new NPCs, buildings that were barren or "locked" can now be upgraded and able to be entered. New fighting moves, styles, little things to buy, whole new areas and cities, etc. Basically it would breath new life into the game even 17 years later till the next game.
Another advantage is if there is a crippling bug and the game team decides not to fix, the community can. And they can even make the graphics better themselves for the whole community. Maybe even get it online. Unless the game developers make the game purposely unmoddable, Shenmue 3 has the potential to be 3.2, 3.5, or more, even 4 if there was no official 4th game to come.