What is more visually significant, an anterior or posterior located cataract?

Cataracts that are posterior are more visually significant. This is because the closer you get to the nodal point of the eye lens system, the more light rays will be affected by a lens opacities. Seemingly small PSC (posterior subcapsular cataracts) can severely affect the vision. Also, congenital cataracts located posteriorly are more concerning for developing amblyopia.