Good question John, I would say that ‘me caes bien’ carries the nuance of someone making a good impression on you so would perhaps be better said when you first meet someone or if you’ve only known someone for a short period of time.
If you’ve known someone for a while and want to tell them that you like them then ‘me gustas’ would work. But I would think carefully about what you want to communicate with that phrase because just like we’d be unlikely to front up to someone in English and say ‘I like you’ without giving them the impression that we were romantically interested in them, the same would be true in Spanish.