To me it would be Revan of focking course, a sith that is not JUST a power hungry psycho, or well maybe he is it is hard to tell....
It look honorable and all that stuff but you know....
During his fight aginst mandalore the ultimate Mandalore applaud Revan for his courage, the courage to face the mandalorians where the Jedi flee and the republic navy was hidding behind a wall of civilians, Revan had a sens of honor, and was also the ebst opponent they have ever faced, To them Revan had a chance of Justice (AKA he just put a mandalorians mask on his face.)
Mandalore the ultimate even proposed Revan to join him and take command of the mandalorians, but Revan just laughed at him :
"I am no Mandalorians you fools, I have other reasons to fight than just the pleasure of crusing my ennemies."
After the fight Mandalore the ultimate Realize that Revan is using some sith technic, and it remind him that he know the sith, he have been contacted by the sith, and all this war is all part of the isth scheme, he realiaze that Revan is an horrible person, but it is too late, he have already betray his peoples, he have enslave them to the sith will, promising them the freedom that fighting procure, he has promise them revench, when they are just tools serving the revench of another, he tell Revan that the one that are aware of the sith influence will retreat toward their true master after the battlle, and then he ask Revan what will become of him, Revan promise him death, and freedom from his ethichal nightmare, there will be no more mandalore, Revan hide the mask of the mandalore after having the greatest mandalorians of all time decapitated in front of all this men, with a speech saying just do not **** with Revan...
Hum thinking about that Revan say truth will be found in blood.. Is he talking about the Cathari genocide or Malachor V.... or both.. Maybe teh first option...
But no KotOR era sith lord sob....
Brotherhood of Darkness..... Nobody they are not true sith, they are just dark side lunatics...
For teh rest everybody god damn know.