They are all amazing shows but Horimiya is my favorite because it's nothing special just a highschool romance anime that does amazing in its genre.
Before watching Chainsaw Man,note that this anime is TV-MA so just some caution,MHA has some revealing clothes and some moderate violence but nothing too bad.Blue Box and Fragrant Flower are TV-Pg so nothing bad.Horimiya is TV-14 for some suggestive themes, a fade-to-black scene, and mild swearing.One of the characters like getting yelled at.