George S. Ledyard
Since these shapes are symbolic representations of states of energy which are fundamentally integrated, it would be silly to even think of things in this manner... no different than saying, "I really like Yin, not so big on that Yang stuff".
When I answered, I didn't like picking one shape over another, but I read the question as asking simply if one of these symbolic forms seems to dominate my movements. In a similar way, I've heard people refer to my own sensei as going through phases where his technique was more yin or yang, though of course there should be both at the same time.
Then again, trying to distinguish between a "triangle" emphasized technique and a "circle" one, I'm having some difficulty. So maybe speaking in terms of movements, this question doesn't work as well, but what do you think about the question as refering to a mental emphasis on entery, blending and, projecting? I know for me these three ideas often come to mind, though almost never as "triangle," "circle" and "square."