Darth Sidious: 6/10. Not a maximally edgelord aesthetic. Spends much of his life pretending to be an inoccuous good guy, which is diabolical but not edgy. Also by the time his aesthetic becomes more edgy, he's well established as an authority figure, which is not a particularly edgy role. Edgelords are more about tragic rebellion than ruling: so in this respect Sidious is a victim of his own success. All of *his* rebellions were successful, which *is* tragic, but not for him.
Darth Tyrannus: 4/10. Look, cut him some slack, he's not used to this Sith stuff. Still, he does have that tragic rebellion thing going for him re: the Jedi and Yoda.
Darth Plagueis: 5/10. Leave him alone, he just wants to do his evil science. Scalpels are edgy, right? Anyway surely he can just delegate the edginess to his apprentice? He wants to get back to his experiments. Little too much authority for the necessary rebelliousness, and takes *forever* to rebel against Tenebrous, though he does try to (unsuccessfully) end the rule of two.
Darth Maul: 10/10. Someone understood the assignment. Classy all black attire. Single earring. Double-bladed lightsaber. Rebels against Sidious multiple times, but never vanquishes him. Dies tragically trying to get revenge. Maximum edge.
Darth Vader: 8/10. Solid edge aesthetic and history of tragic rebellion, but gets points deducted for position of authority in the Empire.
Darth Bane: 8/10. A little too successful so gets a deduction for that, but the aesthetic and rebellion are *off the charts*. Guy rebelled against his father, the Jedi, *and* the Sith. Not to mention the face tattoos and invincibility beetles have incredible edge energy.
Darth Zannah: 8/10. Again, too successful for maximum edge, but solid aesthetic with the face tattoos, plenty of rebellion, and a tragic willingness to sacrifice her closest relative for her ambitions all makes her Edge Factor competitive.