Size is good for you. Skis with that much rocker ski super short, and its really easy to pivot, smear, and move around. I'm an inch taller than you and I ski 191 Wrens which are much stiffer, and use to own 189 bents which are a lot longer & heavier than your One lifes.
179 might be a bit better for park, but its gonna be a lot worse for everything else, like the skiing pow, stability @ speed ,dropping cliffs ect which is a lot more important for a ski like that.