Here is a good setup:
-Silencer, fast mag.
-Perk 1 ghost, Lightweight
Perk 2 toughness, scavenger
Perk 3 Dexterity.
This gun has long range and moderate recoil meaning grip and long barrel are waste of attachments.
It's reload time is really slow so fast mag is the best option. I choose silencer just to not attract attention.
Lightweight makes you super fast. Scavenger just never run out of ammo. Dexterity climb faster and your gun will be readied faster. Ghost so you won't appear on radar when the enemy has UAV. Toughness, no flinch well there is flinch but it's less. Score streaks UAV, CUAV, Orbital VSAT/AGR.
Use CUAV only if the enemy manages to get Orbital VSAT. :D
I may get a lot of hate for this but, the FAL is pretty good in most situations if used right. With a good trigger finger it can mow people down in just 2-3 bullets. CQC may be a challenge around submachine guns, but if you put quickdraw on it you can get that first shot. Medium to long range is the best for the FAL, it's recoil control is amazing. I'm not sure about what other attachment is best, but i know quickdraw is pretty decent. To sum it up, the FAL with quickdraw (maybe stock) and a trigger finger is my way to go.
Depends on you man. Every weapon has its own special ability. The SWAT-556 is perfect for watching over objectives. The PDW and MSMC are more of a aggressive play style. The AN-94 is more of a pushing objective gun. The FAL OSW and SMR are high damaged weapons.
Personally my favorite guns are: AN-94,MSMC,PDW,SWAT-556,M27and Ballista. Black ops2 has balanced guns meaning that there are no dominate guns that everyone uses. I find different weapons on ground rather in mw3 you would find tons of ACR and Mp7.
This is pretty player dependant. You need to have a fast trigger finger (by fast I mean firing at the effin cyclic rate) while being able to maintain accuracy. Most people can't do that. It's the BEST gun in some peoples hands.
Could say the same for the chicom, best SMG in the game in the right players hands. Same RoF as the scorpion and the best recoil of any smg. Drops people in the blink of an eye with practically no burst delay.
I mostly play core TDM and for me it's the R-870. I'm pushing 25K kills with it and it just works for me. Second I'd have to go with the Skorpion.
Like others have stated, there are a lot of variables. Game mode, style of play, sensitivity settings, playing alone or as a team, etc that in my opinion can change the productivity of any given weapon.
R-870 (laser, long barrel)
Perk 1 (greed) (light weight, ghost)
Perk 2 (scavenger)
Perk 3 (engineer)