Formal:
* Ikinatuwa mo ako. (This literally means "You made me happy," but conveys the sentiment of smiling)
* Naging masaya ako dahil sa iyo. (This means "I became happy because of you.")
Informal:
* Napangiti mo ako. (This is the most direct translation and the most commonly used.)
* Kinikilig ako sa 'yo. (This means "I'm flustered by you," and implies a romantic feeling)
* Napapangiti mo ako. (This means "You make me smile" and suggests a regular occurrence)
Romantic:
* Napapangiti mo ako sa tuwing nakikita kita. (This means "You make me smile every time I see you.")
* Ikaw ang nagbibigay ng saya sa buhay ko. (This means "You are the one who brings joy to my life.")
The best translation for you will depend on the context and your relationship with the person you are speaking to.