We need a wing first and foremost. Somebody who can hit the three but also drive the baseline.
A stretch 4 would be nice, but won't Childs become that? Or do you believe he's too short to be a stretch 4?
We need some defensive stoppers along the guard line and some reliable outside shooters. We need so much that it hard to know which key player with make the biggest impact, but if I had to choose one, I would choose a good wing player with defensive skills.