In my opinion, video chat is better. You can see who you're talking to. Also, if you're a sarcastic person like me, the person might take what you say the wrong way when they can't hear your voice. On the other hand, you can be more open with text chat. You can usually say more than you could with looking at their face.
Depends on the context - but since so many people are miss-understood by text's - at least with video - you can hear and see the other person's expression - texting has destroyed the art of conversation.