It's hard to say for sure. Both the anime and manga of Jitsu wa Watashi wa have their own fan bases, and popularity can vary depending on personal preferences.
I'm not sure if Shinagawa Kaoru drew the Tachikai manga because I can't find any information about her. If you can provide more information such as the title of the work or the name of the author, I will try my best to help you.
The appeal lies in its combination of beautiful illustrations and a compelling narrative. The characters' development and the unexpected twists make it stand out.
The story of Kotarou wa Hitorigurashi manga centers around Kotarou's solo journey. It shows how he copes with daily life, makes friends, and faces difficulties, all while being on his own.
Overall, the Aku no Hana anime and manga have their own unique qualities. The anime might have changed the tone or presentation in certain parts, but it still has its own appeal. It depends on personal preferences.