I'd probably go for 185cm but it depends on how you ski.
177cm will be easier to maneuver so they'll be better for making short quick turns through trees and stuff. They'll also be easier to do swaps on rails and spins.
185cm will be better for charging hard and going fast as they'll be more stable and less likely to chatter at high speeds. They'll also be more supportive on big landings.
I like to ski with loose underpants or boxers on so my balls can swish around and chill.
as said above you could ride either. The 177 would be way more fun for you in the park. But they would be a little unstable all mnt at speed. This is te issue with trying to get one ski to do it all. Overall decide if you want to spend most of your time in or out of the park. If your a park guy go 177 ( well go punx actually) if your more all mnt go 185.