Re: Are the Borg the perfect enemy?
'Q-Who', 'The Best of Both Worlds' and 'First Contact' were the Borg at their best. The episodes because they were an unstoppable force without a face.
I think it's impossible to continue to have them as a threat when the episode and future appearances require a conclusion and victory over them. Same with the Daleks and Cylons.
"It's not that you can see the strings, it's that 40 years later you're still looking at them." - Steven Moffat
"This movie was big. Imagine how big it could have been with me in it?" William Shatner