After thinking about it the following were my top three;
In third place is Endless Night, a gunmetal grey metallic which leans slightly blue.
Second place is Holo Be Thy Name, a dark black linear holographic polish. Hard to make a dark holographic because the partials that do that are grey which lightens polishes. I like this one, the bottle is unique too.
Picking between the top two was difficult, however Orbit won because I own quite a few black holographic polishes and Orbit is unique. It is a grey to red ultra multichrome polish, similar to ILNP Eclipse but grey rather than black.