It's more about weight. But if you're 6' and 130-140 you should still get long skis, if you're tall always get long skis. If you're short, get appropriate sized skis and get them longer if you weigh more.
at your height and weight a 171 is fine. Im an advanced to expert skier who has worked in a shop for years. and with that size you will be fine. Im 6' 170 pounds and my park ski is a 170 and it works perfectly fine for me. it even works for BC skiing on shitty days.