Pretty sure Harbinger says the Drell are useless because there aren't enough of them left. So clearly there's a minimum biomass threshold for a new reaper to be viable. Kind of makes you wonder if there were relatively few Leviathans that went into creating Harbinger, given how *huge* they are. Maybe in the tens or hundreds of thousands rather than billions?
Can't really see it being the Hanar. Nor the Volus or Elcor. I say the Batarians since they're most like the humans, more so than the other races at least. I suppose you could say the same about the Turians, but then Harby called them "too primitive" whatever that means. Perhaps they're just to rigid and I'll equipped for adaptation? The Batarians seem adaptable, aggressive, ambitious, their only real weakness was their political system and I'm not sure how much that'd figure into things, one way or the other.
The "You wouldn't know them" line always cracks me up, largely because of the response it gets on BSN. Frankly though, we wouldn't know them, so what would be the point of assigning them an arbitrary name?
Not that I disagree, but you must admit it does rather smack of lazy writing. But then the whole bit about every race down the ages adding to and developing the design and yet somehow none of them have a clue what it's original function was just makes no sense.
One of my theories up until the Starchild scene was that it was a supernova generator. Tying in the dark matter/ageing sun subplot from ME2. The basic idea being that it uses the mass relays to selectively target the suns they orbit and make them go boom, taking any reapers in the system with them. I thought the "big decision" would be whether to sacrifice Sol and humanity to take them all out at once, or (with low EMS) set them all off, hitting the big resent button for the whole galaxy.
I'm not saying my notion was any better, but at least it makes some semblance of sense. It's also why I barely hesitated to pick destroy in the end, since I went in fully prepared to sacrifice one race to save the others. It's sad to loose EDI & the Geth, but they both expressed in the game that they'd rather risk non-functionality than allow the reapers to continue.