Afraid I don't know the Borg. I'm not much of a sci-fi fan. Warhammer is more fantasy-in-space. It even has Orkz. :p

Not sure what else to talk about in here though, since I don't know much about the other factions besides the Imperium. I mean, I have cursory knowledge, but not really enough to hold a discussion about.

There sorta like the Star Trek equivalent of drow back when drow were actually mysrterious and scary. Humanoid cybernetic people that travel around in large ominous rectangular ships that assimilate (important word there) other races and such into their consciousness.

'We are the Borg. We will assimilate you blah blah blah, resistance is futile' or something along those lines. I'm not a Treky really but I'm sure someone who is will fill in if I'm sorely misinforming people.