So before PSN went down I was playing black ops... I like playing the 12-18 man games (domination and ground war) primarily because if I suck, i'm less likely to get singled out. On the other hand, I'm actually doing better, surprising finding myself not infrequently in the top three and even in the number one position a couple of times. I finally got my own copy yesterday, and my roommate really likes headquarters games, so he's dragging me out of my safety zone.
For ground wars, I've been going with the ak47u setup pretty similar to drummer described. For domination games, I've actually ended up going with the M16 with the blue heat scope. It works out good for me both for defending from a safe distance, and is also reasonably fast if I need to fire off shot when running around the map. I also use second chance with my m16 build, because those extra few seconds clinging to life may be all I need to capture the objective.
I'm way more into this then I ever got with CoD4.
What is really killing me is that before the network went down.... I was at 49 1/2 to my first prestige. This outage is really making me insane.