Genocide is the argument that continues to confuse me.
Genocide - systematic killing of a racial or cultural group.
The Borg are an amalgam of various species they've assimilated over the years. And with a single hive mind I see little in the way of a good argument that they have a unique culture and that the universe would be losing something if they were eradicated.
The Borg at this point are nothing more than a wondering computer program executing a set on instructions given to it untold years. Picard should have pulled the plug.