easiest, hardest, favorite, least favorite extras?

[Buwako]

i personally have not beaten an extra stage yet. (i think my highest chance right now is mokou) but im sure there are some of you that have so i would like to know what you found easiest and hardest, and if you have any favorites or least favorites.

 

[UnofficiallyKishinjou]

easiest is ran, hardest is kaikidan alice, favorite is flandre, and least favorite are the getsu sisters.