너에게 마음이 있어 너에게 감정이 있어 I think they are both fine, but if you're saying it verbally, 너한테 might be better. Also, there is another 감정 (same spelling, but of different hanja) which means a grudge or chagrin, so the second sentence might be taken wrong (although in reality the context usually makes it clear). For example, 너 나한테 (무슨) 감정 있니? said in a serious tone means "Do you have something against me?". If you make it 너한테 특별한 감정이 있어, it might convey the sense more clearly.