If Soubi has to choose a new master it would probably be...Fuuma. He'd go with Lelouch, but things are awkward in that direction already because of Suzaku, and Fumma reminds Soubi of Seimei, but is different enough from him that he wouldn't be trying to replace Seimei with Fuuma. because no one can replace Seimei.
If Kitty could pick one person she could send home from Marina, who would it be?