Who saw the most of what happened? Who has the least at stake in testifying? Who was merely an innocent bystander observer? A defense lawyer will rip to shreds anyone who is testifying. If the person is unrelated to you and has absolutely nothing to gain by coming forward on your behalf, they are the better witness.
Prepare yourself for questions attacking why you waited to press charges. I do not say that to be mean but it will be a question. Seen it too many times. Just be ready.