I think the Borg's 'effectiveness' diminished with Queen's introduction.
I liked how they were handled without one in Q: Who, TBOBW and Scorpion.
They were actually like a force of nature in those episodes.
The queen was nothing more than a gimmick to cater to the masses because apparently the public is too stupid to envision a concept of a hive mind without a leader of any kind.
As the Borg described humanity in TBOBW: "Your archaic cultures are authority driven."
And that's what sets them apart from others in the galaxy.
It's that they were based on a concept which most humans (but not all) were incapable of envision to work in practice.
For crying out loud, even TNG started out while being based on concepts that contemporary majority of people were not able to digest entirely.
They keep saying money doesn't exist in the 24th century, and you have people who keep coming up with ideas that would effectively kill that premise simply because they cannot wrap their minds around the thought that human society is capable to function without money.
As the shows progressed, the characters and their mannerisms were turned effectively into early 21st century humans... just in space, and kept forgetting how to use the technology at their disposal because the writers apparently were incapable to write the drama around the setting.