All things being equal, especially after so many years, I think I definitely prefer "Scorpion" to "BOBW." It's not a question of visual effects. Over the years, I've just come to realize that I greatly prefer the Voyager characters to the TNG ones. That said, my favorite parts of BOBW have nothing to do with the Borg. I much prefer the quieter scenes, like the one between Picard and Guinan when they discuss the oncoming battle, the scene between Deanna and Riker about what he really wants and how he's not as ambitious as he used to be, and the "That is now your chair" discussion between Guinan and Riker in Part 2.