The quality of a girl correlated with her ability to be exploitable for reaction images. This is why everyone loves Marcille from Dungeon Meshi or Albedo from Overlord. This still holds up for Killing Bites: even though Hitomi isn't very expressive, every single separate "THAT'S WHAT KILLING BITES IS" counts as a separate reaction image, increasing her qualities as Best Girl.
Hell, Shinozaki-san's crazy faces are pretty exploitable too. Shame nobody fucking posts them.