Gargs have pretty decent claws and use them to grab on to the bark of trees and their branches. If you look at a crestie on glass, and compare their feet to a garg's, it's pretty easy to see that the gecko's feet are "better" at creating Van der Waals forces. CGs have claws too, but I do find they do better on smooth surfaces than gargs.

Regardless, I find that they all just prefer rough surfaces. My cresteds like to hide behind leaves and in plant-y stuff, while my experience with gargoyle geckos leads me to believe they're a little more tolerant of just chilling out on a chunk of cork bark in the semi-open.