Vader and Maul..theyre just the coolest..even though those are like ur stereotypical sith's every1 knows about and likes, i dont care theyre just both awesome..i love maul with his dual lightsaber and martial arts skills and his acrobatics....watching the lightsaber scene with him obi wan and qui gon was just too cool...best lightsaber fight out of all 6 episodes IMO..and Vader, because, simply, well he's vader....he is just so powerful..even though he may lack the agility and quickness because of his limbs being severed...hes just so pimp in that lifesupport armor, and the way he breathes lol
Tulak Hord. His past is one that's still not tampered with. And he's not as "Uber 1337" as some of the others. Sure he's the greatest Lightsaber duelest ever, but there was always room for someone else to take his place in between his time and where the Post-ROTJ timeline ends. I also like Marka Ragnos 'cuz he's badass. When he reigned, no one dicked with him.
Definetly Dooku, he as class. He's a succesful politician, the Count of Sereno (mucho richo!) and a classical swordsman with a cool lightsaber. He seems to generally have a nobal cause for founding the Confedracy (to free the Repbulic from corruption) although theres the slight mishap of falling to the darkside involved.
Also Revan, also follows a noble cause, also has alotta class, amazingly clever and seeks knowledge (pretty much a force powered uber geek!) who's amazingly powerful aswell. I like the cloak aswell, very scene. He also has a single saber (in KotOR 1), so he obviosuly hasnt sold out for this saber staff fad.
As for Maul...there is nothing remotedly interesting about Maul. he's crap. Saying you like him is like saying you wear shoulder pads...