Borderlands hands down. Sure the idea of the major businesses being arseholes and the general bad guys isn't new, but the content is entertaining and plentiful. The weapons certainly give you reasons to go get them (I <3 CC). Hell it even makes an old idea actually sound amusing and worth doing over and over again. Most folks that say other wise are either being haters for the sake of hating, never played the series, or have different tastes in games.