You got replies that cover 2 common theories on ski sizing. Use height, weight and skier experience to choose a length, or pick a ski based on height, weight, skier experience and then map that range of lengths to skier types. The first points toward 185, the second towards 177, as 177 is one down from the top ski which would be for hard chargers or heavy people. The corollary for both approaches is that only a demo of the skis can tell you for certain which length is best for you.
Just to muddy the waters, the shorter length will be a little more nimble, the longer will be more stable at speed. If one of those 2 is a challenge for you then lean towards the one that will help in that area.