The term "sunnier" typically refers to something that is brighter or more cheerful. There are many synonyms that can be used to describe these feelings, including happy, joyful, optimistic, buoyant, and radiant. Other possible synonyms include cheerful, bright, upbeat, luminescent, blissful, merry, and gleeful. All of these words can be used to describe a variety of situations, from someone's attitude to the weather outside. Some synonyms may also hint at a more romantic or emotional interpretation, such as radiant or blissful. Ultimately, the right synonym will depend on the specific context in which it is being used.