There's this theory that graded papers are sharper than VC papers. It may be true, but it could depend on various factors other than the paper, like the light source and filtration.

My theory on this is that VC papers have a wider spectral response than graded papers (otherwise the filtration wouldn't work), so they will show up chromatic aberration in the lens more than graded papers, depending on the filtration, the lens, and the light source. If you use an apochromatic lens or a narrower band light source or a strong monochromatic filter, you shouldn't have a serious problem with chromatic aberration, so you might not notice a difference under those circumstances.