I think Garrus is my favorite too. I dont see why you dont like Javik though. He brings a realistic view to the current circumstance. Id take his cynicism over that whiny ensign's blind idealism.
What do the Reapers want with Ardat-Yakshi? Oh, yeah, I couldn't possibly think of a reason why the Reapers, who are trying to kill all intelligent life, would have an interest in unstoppable murder machines.