Otori-san is honestly one of the best characters in this whole manga. Most characters have some preconception about Komi-san, like "a goddess to be worshipped". Even Onemine-san thought Komi-san was bullying Tadano-kun at first. But Otori-san just saw Komi-san having fun with her friends and thought "I want to be friends with her too". Otori-san is the first character to treat Komi-san like a regular human being without any help from Tadano-kun. And her unprejudiced approach led Komi-san to be comfortable enough to speak out loud with her quicker than any other character, Tadano-kun included. All because she just treated Komi-san like any other girl.
tl;dr Otori-san Best Girl