Whatever you're comfortable with. If you're really good and able to handle yourself when you charge hard, then get longer skis. Remember that skis have different rises, so some skis will ski shorter than their size indicates
This is correct. However I'm 5'9 too, 160 lbs, and consider myself to be a decent skier and I have 171 pipe cleaners. I probably coulda gone with 176 too if I wanted them to be a little more all mountain. Just for reference