Composite Ver. Ka.
Beyond all the obviously cosmetic and fancy patterns stenciled on the Composite Ver. Ka's body, it also boasts better articulation, overcomplicated detail, much more armaments, a much larger shield system, and generally better proportions. The Robot Tamashii is much more anime-accurate, but the proportions (arms are super-slender and reaaalllyyyyy long) and aesthetics just aren't as good as the Composite Ver. Ka's.