Usually it would be he's/she's good to me and it means that he/she treats you well, they do nice things for you. It's good for me means that something is beneficial, for example, healthy food, sport etc.

Someone can be ‘good to you’ Something can be ‘good for you’

It's good to me means it may not benefit others. But I love it. Actually, there is no difference between them. But if you translate them into your native language, you will realize the difference.