And I don't agree with you all. The Borg had to have weaknesses in order to be interesting, otherwise everyone that encountered them would have been assimilated and then no more show. The Borg always were weak in certain ways and the more we saw them the weaker they became, they simply don't work any other way.
I thoroughly enjoyed seeing the mighty Borg meet their doom at the hands of Janeway and Picard. They were on borrowed time anyway, such a society could only grow so long as they could assimilate technology, they couldn't create. It would be inevitable that one day they would meet the Society they couldn't assimilate or the one with the power to resist. The Federation had the cohesiveness of the collective without losing their individuality, and therefore their creativity. The Borg were simply not smart enough to fear them.
The Borg were doomed from the beginning, but once the Federation became aware of them that doom was sealed.
In fiction the only interesting villain is the one you can defeat, otherwise the story goes nowhere fast.