I've got all the primaries and have had a chance to use them. Here's my verdict, so you can go do the opposite:

Oversoul Edict - Good for a pulse rifle. Might even be great when they get their buff.
Abyss Defiant - average, but very situational. The Wizard disorientation perk is really good if someone in your group has it.
Fang of Ir Yut - Really good. It's basically an arc VoC without autofire. I'd go with filed scout though since it has only 15 shots by default.
Word of Crota - Sight gets in the way, and the gun is hard to aim. Okay. Good for void burn I think.
Necrochasm - sucks

Fang of Ir Yut is definitely the best of the bunch.