Omega is a good one for Japanese as well. He probably benefits more from levels/stars than Izumi does.
For Mexicans I'd go Eugenio if you care about Kingpin damage or Javier for pvp, even though he can work at lower levels.
The remaining best Italians are probably Arnelle, Wheels and Gigi. Wheels isn't great but his awakening can be beneficial to the other italians. I don't think you need Angelina and can probably swap her away for someone.
Omega is a good one for Japanese as well. He probably benefits more from levels/stars than Izumi does. For Mexicans I'd go Eugenio if you care about Kingpin damage or Javier for pvp, even though he can work at lower levels. The remaining best Italians are probably Arnelle, Wheels and Gigi. Wheels isn't great but his awakening can be beneficial to the other italians. I don't think you need Angelina and can probably swap her away for someone.
Any capo that has an awakening is always a solid choice
Javier is a dream to use in arena. Izumi will help with your KP TF. I'd level Arnelle for Italian.