Infamous 2 is a game i bought for the plot, (which i great by the way, no spoilers but both karmic ending are awesome!) . And the building up of your character, i find fun! from weak at the start to godlike at the end, all the meanwhile keeping the game fun. After finishing the game you can hunt down achivement, (i think there are 3 platinum in this game!) or play UGC missions. (player made missions that are shared to the community to play.)

Black ops is more of a game for the multiplayer. i play with friends and only enjoy it if i play with them. the campaign is extremely average, and is more to do with just teaching you the basics of the game. After a while though you may love the game for its multiplayer due to be being a good player. i myself like the thrill of dominating the other team.
~Yahoo answers