In Call of Duty: Black Ops for the PC, PS3, Xbox 360, and Wii, each game type gives XP in slightly different ways. Some game types give a little more than others, but they’re still fairly close.
So which type is the “best” for giving fast XP? Well honestly it depends on your style of play and which game types you’re best at. A lot of the top tier players swear that Search & Destroy gives the most XP per game, but if you’re not good at S&D, then it won’t pay off like it does for them.
For example, I’m best at Domination, so I personally level up fastest playing Domination, because I get points for kills, taking domination spots, defending the flag, taking out spy planes, etc. Sure I can get equal points in other team based games, but I’m not as good at them so I wouldn’t get as many points in the same amount of time I would get out of Domination.
Generally speaking though, the team objective games are faster XP, unless you’re really good at deathmatch games and can win the majority of your matches or at least be near the top. If you’re that good, it doesn’t really matter though and you’ll level up fast in pretty much any game type.