Formal:
* Kilala ba kita? (Most common and formal)
* Nakikilala ba kita? (Slightly more formal, emphasizing recognition)
Informal:
* Kilala kita? (More casual and used with friends or family)
* Parang kilala kita? (Expressing uncertainty, like "Do I know you from somewhere?")
Other options:
* Nakita na ba kita? (Have I seen you before?)
* May alam ba ako sa'yo? (Do I know anything about you?)
The best choice will depend on the specific situation and your relationship with the person you are asking.