The Great Conflict

You are now surrounded by five lizard creatures approximately an average of five meters away from your location. They have glowing red eyes, spikes covering most of their scaled body and seem to have a very large amount of muscle. They have massive arms the length of their entire body equipped with a set of razor sharp claws. Judging by the size and musculature of these creatures a single swipe could be fatal. You are only going to have one shot to take them out before they are within melee range and tear you to shreds. The only choice left to make is which weapon to use. You have your plasma enhanced assault rifle, your energy pistol, or your antimatter charge. Which shall you use?