Stabilty, magazine size and rate of fire . If it's to fast like the Dead Orbit one you will miss some critical shots which results in dead but if it's to slow you'll have a disadvantage at close quarters. I personally like the Silvered Hushwind-D the most. It's good at close/mid range and the magazine size is respectable. Shingen-C and/or E are great AR's too. But.. If you really want the best, the Suros Regime is the one to grind for. The ability to slowdown rate with more damage while RDS'ing is awesome for Mid/Long range and if in close range you just hipfire with an increased rate of fire. :)