We all know Inoue is one of the best fighter in boxing nowadays cause still he can prove tonus that he is the monster in every fight of him. And yes Inoue nowadays still don't have losses so he is undefeated but as I observe in his achievements he fought in his homeland which is pretty good enough cause he is the advantages cause his homeland is his comfort place to fight. But we must see the more exciting to watch once he go outside and fight in different countries.
IMO, he does not have much of an advantage fighting in Japan since most of his fights end up via KO wins. Maybe a little bit of inspiration fighting in front of his supporters, but he also fought in the US and we still saw the same outcome. Inoue is so hype right now but honestly, I don't see him as good as those boxers that are also a top pound for pound boxers.
As per ranking here :
https://www.ringtv.com/ratings/1- Terrence
2- Naoya
3- Usyk
4- Canelo.
I believe the best in this ranking is Terrence, because I see that he has more quality opponents, probably 2nd is Canelo and I'll put Inoue on the 3rd.
This is just my personal opinion though, you might not agree with it, but it's okay.