Like Hammer has said, communication with your team is more important than any gun layout that you could use. You could have the most ideal gun, perk, killstreak setup for the map that you are playing, but if you don't communicate yours and enemy positions to your team, it's all for not.
The type of team that you are playing with has a big factor as well. If your team is mostly all run and gun, then there isn't much sense in using a camping class with high kill streak rewards. Better off using fast running class, smg, nades, hardline to get kill streaks faster and lower kill streak rewards because you're more likely to die a lot running around.
If you team posts up to guard a side of the map, then I personally like a silenced class with claymores, cold blooded, scavenger and sitrep. I use higher kill streaks since you are more likely to get on a roll against runners that way and can get the greater kill streaks going.
But still the best thing to remeber is communicate, communicate, communicate!!
Good luck out there!