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.
I would not really put Canelo as high as #2. His record looks impressive but a lot of his opponents have been past their prime. When he's been in the same weight class as dangerous knockout artists like Golovkin, Beterbiev, or Benavidez he will completely avoid them for as long as possible. Inoue and Crawford have not had any losses or controversial decisions so to me they deserve to be considered the two best fighters in the world.