I guess, that for some, a dog is fine too.

Number 4 is out. Like outside. In the yard. Where my dachshund lives.

B4 Trans: 1-3 all sound good, but I assume the text describes her personality.
[cringe warning: headcannon fanfiction looking text]
My ideal Shigushigu is the typical well discipline, quiet, and amicable shipgirl, but with hidden PTSD switches for either gouta "too bad for you" mode or night battle mode. Loyal, of course, but only as much as you are to her, and none of that irrational yandere junk. Yandere intimidation to maintain control for commander retention and defense is fine though.