King GM Gun Since Patch?

I have heard that the best GM gut is the G36k/XM8, but because of the two new GP guns is it still this way, I am currently a Sarge FC and I could technically buy the M12s but I am patient enough to wait till SSarge Class 4 to be able to buy any of the GP guns, so tell me, what gun should I get, I have tried the M12s and it does a splendid job, but because of the ammo compacity I am a little hesitant on buying it. I have heard that the Tar is excellent as well, but yeah, what should I get to go with my DEagle.