The A280 is a good overall weapon (improved cooling and improved range are its best mods), and works well at all the distances although it requires better aim and precision than the CR-2 so in case of doubt choose this one. The CR-2 (reduced recoild mod is a must) is excellent for close quarters due to its huge rate of fire, but really bad to take down far targets because of its spread and low damage, so it is the best assault weapon for maps where engagement is close and personal. Actually there is not a best weapon for each class, most of the weapons have strenghts and weaknesses (it is important to have the mods for each one of them though, they improve the weapons a lot) and therefore you have to choose the one that suits you depending on playstyle and the type of map, here is how I see it:
