@RedRaptor
I agree and disagree with you. Bad guys don't have to be so 1-dimensional, give a bad guy just as much character as you give your main characters. Make readers unsure of who they actually want to see win, and you'll make a hell of an interesting conflict.
Where I don't agree is the "ever boring 'crazy for murder' guy" part. Characters aren't boring because their traits, they are boring because how those traits are executed. One of my favorite characters of all time can be boiled down to "crazy for murder" but she actually has an agenda and don't kill thoughtlessly, has a soft side, has been the main support when the MC needed it multiple times and overall the most interesting character in that series.