In the game from which Brad McQuaid copied almost everything when he made EQ (SojournMUD, since renamed TorilMUD), shadowknights (there called anti-paladins) were
only allowed to be human. As such, it is the
morally correct choice. Only humans have the concept of knighthood. It's the original D&D-based canon that EQ plagiarized wholesale.
But human isn't mechanically optimal. Ogre is, unless you play SSF, and then it's troll or iksar.
Mechanically, human is shit. Canonically, it should have been the only eligible race. I went with human, but ogre is just better.