Bioshock, and I say that after having played and beaten all three.
It had the weakest game-play of this group. While the narrative was good, it was still mostly a corridor shooter where you didn't have inventory room for some of the more interesting weapon types and most of the powers weren't worth bothering with. Unlike the other two, there was very little room for improvising or using different playstyles. The ending was also on the lame side and I felt sullied by the unsavory decisions of characters I once liked.
Far Cry 3 is the second lowest. The game-play was fun but it was let down by an unlikable cast of characters and a throw-away narrative. It also suffered from having to walk around too many mountains, something which was improved greatly with FC4.
Borderlands 2 is at the top by a comfortable margin. Strong game-play, enjoyable story, GREAT characters, and a ton of improvements over Borderlands make it one of the best games of last generation. Unlike the others, it offers a ton of replay value, as you have several playable characters who each have a selection of different playstyles.
