Formal:
* 高興 (gāo xìng) - This is the most formal way to say "happy," similar to "delighted" or "pleased."
Informal:
* 開心 (kāi sǐn) - This is the most common and informal way to say "happy," similar to "joyful" or "content."
* 歡樂 (fān luò) - This is also an informal way to say "happy," often used in the context of having fun or celebrating.
Other options:
* 快樂 (kuài lè) - This is a slightly more literary way to say "happy," meaning "joyful" or "blissful."
* 幸福 (xìng fú) - This is a more intense way to say "happy," implying a deep sense of contentment and well-being.
The best way to say "happy" in Cantonese depends on the situation and the person you are talking to. For most everyday situations, "開心 (kāi sǐn)" is the most appropriate choice.