About the Borg on VOY:
I get annoyed every time someone says there was "too much Borg". In my opinion, TNG used it, a few movies used it, many novels used it. The Borg got used pretty much everywhere except DS9 and TOS.
After watching 90% of DS9 (which I love, I'm on Season 7 now!)...the Dominion were a threat spanning multiple seasons and were shown constantly. I am so sick of them at this point that I just wish the Federation would blow them to bits NOW.
I can honestly say I did not "get sick of" the Borg on Voyager. How can you when you have characters aboard the ship who used to be Borg who you've grown to care about? And the Borg, out of any of the "antagonists" including the Dominion were probably the biggest threat in Star Trek...ever. So the fact that they were the main "bad guys" in Voyager made Janeway blowing those suckers to pieces even more satisfying. Even though she did not destroy the entire Borg collective, killing that
queen was an awesome scene.
The Borg also represented the taking away and removing of individuality...not caring what happens to specific cultures or individuals and only caring about growing larger in numbers and creating more drones. I can't think of any other threat that great. Even the Dominion in DS9 left people as individuals, even though they weren't the most likable or understanding beings. They didn't turn people into lifeless drones.