I can pretty well understand the difference between say, a situation that calls for the sniper rifle or the shotgun (one is better at long range, and one at very close range), but in what situations would I want to equip or activate a SMG vs an assault rifle, for instance? What situations are appropriate for using a pistol?
Say, for instance, I see an enemy that's a bit close for a sniper rifle, but not close enough for a shotgun. What weapon do I reach for?
Or in another way of looking at it, if I have a shotgun, is the SMG redundant? They both seem like they would work well in close quarters. Similarly, if I have a SMG, is the Assault Rifle redundant? They're both rapid-fire weapons.
In what ways does each class of weapon excel? How should I choose between them (either in my loadout or in the heat of battle) based on the mission or the enemies/situations I will encounter?