I've played it in both languages, and I think the Japanese voice acting is a pretty big step up in this case. I actually really liked the Japanese cast in FFX, and while the English dub is definitely among the better of its era (and miles ahead of most PS1 / early PS2 era English dubs of Japanese games), I could see it being a bit cringeworthy by modern standards given how much English dubbing of Japanese games has come on in the last however many years. With something like FFXII, I'd say play it in either language (actually, I think I might even have liked FFXII a little better in English~

), but in FFX's case, I think the Japanese track is definitely still the better of the two.
That being said, the English dub still isn't that bad, and it's not at all something like Grandia or Arc Rise Fantasia where the dub is so awful that it comes close to spoiling the entire game. So I wouldn't call it a deal breaker or anything. Also, I might be a little biased because I tend towards media in its native language, whatever that language might be. Up to you, really.

You could always google videos of the two dubs, and see if the difference is significant enough to you to outweigh the appeal of the PS4 version? Pretty sure there will be playthroughs of both on Youtube.