A difficult category for me, I think the easiest one to eliminate is Rita's Black because it isn't opaque enough in one coat.
The Raven is a very dark scattered holo polish, I didn't find it as holographic as other A England polishes but it is very dark which is what you want for a black.
Second place is Higitis Figitus, the holo is very strong in this one but because it has more pigment in it the darkness of it is lessened.
Which means the winner is Say Boo and Scary On, a very dark navy holographic polish.