I like the left one better...
The front "gear" piece looks like the asteroid is phasing through it or something, as they overlap on both the left side of and the top of that one "spoke". Or the top and right, depending on the perspective you look at it from.
I still think you should add many tiny grey structures on the top (or maybe a few
) to make it look more massive. Kind of like how the death star looks almost like a city when you get close to the surface. Or keep it like that.
