Hi My Sweet Heart and Devil Beside You are pretty similar.
-Both shows feature Rainie Yang as the lead actress in the romance story
-Both are slow paced, and use common Taiwanese phrases and dialogue
-Both feature the heroine encountering romances with several male actors

Hi My Sweetheart and Why Why Love have several common characteristics
-Both feature Rainie Yang as the lead actress with romance stories between several male actors
-Both use simplistic Taiwanese dialogue that is easy to understand and follow
-The heroine encounters multiple loves scenes between the guys she interacts with

Corner with Love and Hi My Sweetheart has multiple similarities:
-Both shows feature Show Luo in a romance with a lead actress from Taiwan
-Both shows use simplistic Taiwanese phrases and languages
-Both feature multiple loves between the heroine and male actors