Storm Shadow.

Reasons:
+ 'Shadow' refers to his blackness
+ 'Storm' makes it match the whole 'storm' theme of the "Neo-Seekers" (e.g. Sunstorm, Acidstorm etc.)
+ Feels more "Hasbro" since it's the name of a G.I. Joe character, and we've often had several Transformers and G.I. Joes who share the same name (e.g. Scoop, Stalker, Skydive etc.) - Storm Shadow is also an uber kick-butt character (as Snake Eyes' counterpart)