may i firstly say that you are a bit obsessed with guns tonight and its a slight concern. secondly it would have to be accuracy. what would be the point of having a powerful or long range weapon if it was too difficult to hit the target?

I'd say accuracy, then range, then power

The most important factor in a firearm use is to be able to control oneself from being trigger happy.

Range is not important as most firefights take place at less than 200m. Besides, the Lee-Enfield .303 rifle could shoot further than the soldier could see. Stopping power is usually increased by having a larger bullet. Say 7.62 instead of 5.56. However, a larger bullet is heavier and the soldier can carry less ammunition. Although, it is important if the enemy is behind cover. As most modern armies use 5.56mm, thy are at a slight disadvantage in urban combat. This is one of the resons for the underslung grenade launcher. Accuracy, is a tough one. In a firefight you rarely have the few seconds needed to aim precisely at an enemy,unless you want a bullet through your body. For a sniper however, it is a different story. To answer your question, there is no definate answer. Different weapons are specialised for their role, the Squaddie needs a light, handy, fast firing assault carbine. The Sniper needs a high powered and accurate rifle. The artillery gunner, tank crewman or lorry driver needs a submachine gun, this is the reason behind the development of the P90. A SAW or LSW needs to spit out bullets very quickly to keep the enemies heads down, accuracy and power are not needed. Look at the Bren LMG for example. It was too accurate for a machine gun. It had to be wiggled around to take out several charging enemies, or the bullets would just all hit the same man. There. That help?