Hmmm, you could really go either way. if you are still growing pretty quick you could probably get more time out of a 171. I would go 171 at your height. ideally you are right in between the 2 sizes, but I think the 171 would be better in the long run.
Unless you are strictly hitting the park and want a small ski to flick around on rails. if you are thinking primarily jibbing and very little outside the park 161 would be ok.