@Pachi Nienami was by far one of my favorites. o/
Mmm, I'm not sure. I think it depends on the situation/opponent. From the more practical standpoint, I agree - in every situation but specially against a stronger opponent, Nienami's would be definitely an all around solution. Considering Iihiko being OP, naturally hers would be by far the best bet. But in a fight where you might need to play more defensive, Mogura's might be more suitable (since as shown in the match against Iihiko, you still need to hit your opponent, as he and Zenkichi kept avoiding each others blows as it was a "First one to hit oneshots"). Just a thought, though, not sure.
I also like Momozono, since she has the "Seal with It!" mentality which lets her seal someone or seal them post death to prevent resurrection and is not afraid to use it.