Black Ops is dominated by assault rifle and smg classes thanks to the absence of having a shot gun as a secondary weapon, and the quick scoping feature having having been nerfed. But there are some great maps and game types that will make the shotgun a weapon to be reckoned with if used the right way. Hanoi, Firing Range, Nuketown, Havanna, and Launch offer great close quarters opportunities for the shotgun to shine. Now when considering what loadout to choose with the shotgun is actually more open than you might think. This is my personal favorite though, Primary: Stakeout w/grip, Secondary: CZ275 w/extended mags, Lethal: frags, Tactical: flash, Euipment: Tactical insertion, Perks: Lightweight, SOH, and Marathon. I like having this set up because no matter what happens, I know i"m faster than most of the other players on either team which give me an advantage in two ways, 1st I can get to the choke points first giving me position on the other team from the begining frustrating them right of the bat. 2nd In one on one battles I can run faster around a player than he can spin. Most people only run a 3 or 4 sensitivity and you'll be able to get behind them easily in close combat situations. I like having a pistol with my shotgun classes because you have very limited ammunition in your mags and you may need to finish someone off or put someone down if you run into more than one enemy. The Tactical insertion enables you to keep up the pressure and generate more offense.
Now if you want to play defensively I think the best option is Primary: Spas 12 w/ suppressor, Secondary: CZ275, Grenades: Nova gas and frags, Equipment: Motion sensor or Claymore, Perks: Ghost, SOH, and Tactical mask. I suggest this if you are playing domination or headquarters because you play alot of defense and they will never know that your waiting for them. Use the claymore or motion sensor to watch your back, and the nova gas will hide your position and disorientate the enemy while you move in for the kill.
Now I'm not saying that the other shotguns are bad, I just prefer these two. The Stakeout has the longest leathal distance and the Spas has an 8 round mag. and can be suppressed. I'll be giving you a looking to rushing later on. Thanks guys!