Honestly - any of those four would be a solid choice. I think I'd go with Hotatsu, though. He's the one who will help keep your team alive most reliably.
I do notice you have a handful of extremely sub-par champs at level 40. I would avoid spending any more resources on any of them, except for:
I also notice a few level 50's that I'd stop spending resources on - Galek, Spirithost, and Heiress.