Its kind of a hard thing to say at the moment. I mean , the battle rifle with a decent boltshot can really rack up the kills fast. A good sniper with a dmr might be able to use the plasma pistol to really do a number on the enemy. The ability to dual wield primary weapons can also be very effective. Then the armour abilities, like the jet pack to get around and escape close combat, the hologram to save you from a stick or sniper, active camo to save your ass and assassinate enemies and autosentry to finish off shield-less enemies. Then there are abilities for more ammo, faster shield recharge and more ordinance drops. This is a hard and bitter argument! Post your favorites below!