Okay, we all know that the Borg are out to assimilate all intelligent life and conquer the universe, but in the Voyager episode "Mortal Coil"
Seven of Nine mentions that the Borg once encountered a Kazon ship but didn't bother assimilating it or even destroying it.
So I wonder, just what are the requirements for Borg candidacy? Superior genetics? Advanced technology? Obviously, but what about specifics? What kind of tech? What kind of biological standards? Also, the Borg all seem to be humanoid in the shows, but that's most likely due to low budgets and lack of decent CGI, or whatever. In all likelihood, the Borg would probably assimilate anything as long as it was intelligent or had some kind of unique genetic ability, having two arms, two legs and one head shouldn't matter much.
So my question is this: What species would the Borg target and why? And not just other Star Trek races, but what if they encountered aliens from outside the Star Trek universe? Such as the Taelons from Earth: Final Conflict? The Scarrans from Farscape? Or heck, the Time Lords from Doctor Who? Discuss!