i think mitsuko in a vacuum, she is probably the most versatile and she will pair well with sorcerer emblems too, not much competition there.
you might consider anzogh but you need good support for him, i talked about this in this thread: Wizard Emblems: Guinevere or Anzogh (or Hel) - #17 by anon82149927
i also had ranvir and inari dilemma and although i have wu maxed, i couldn’t resist fast mana, deals damage extras that ranvir brings. his added sturdiness will also help, i can’t even remeber all the times i had to trigger healer prematurely in various settings because precious wu was close to death.
inari should absolutely be next in line (at least it is for me) if you have okay yelolow damage dealer. i have musashi and jackal and they work well enough so not even joon could convince me to level him before inari now.