Xiaolan. Because in several episodes, Lan and Ai and Conan always think of Xiaolan when everyone is in danger (especially the theatrical version of Trembling Music Score), and they are childhood friends, it is easy to know that Conan and Xiaolan must be in love. For Conan, Xiao Ai belongs to the category of friends. Although it is obvious that Ai likes Conan in several episodes, Conan's usually keen observation is very slow here. So he doesn't like Xiao Ai. If you really like Xiao Ai, you should have noticed it long ago.