Here's some good ones that come to mind (in chronological order):
Darth Xedrix: Sounds cool.
Darth Chratis: Something about the way it sounds is intriguing.
Darth Thanaton: Kinda rolls of the tongue
Darth Bane: Bane has kinda a badass connotation to it and sounds cool.
Darth Zannah: The meaning behind the name greatly amuses me.
Darth Tenebrous: Sounds cool, means shadowy.
Darth Plagueis: Something about this name just sounds unique.
Darth Tyranus: Sounds badass as **** (a lot more badass sounding than Dooku IMO)
Darth Vader: OG Sith name. This was the name that made Darth a thing.
Darth Revan. I always liked how it was closely associated with Revenge and it's badass
Darth Tyranus. I always, it's a cool sounding name and it matches Dooku's cunning and noblemen-like personality.
Darth Sidious. I don't know, this just made Palpatine better imo, it's just one badass name.
Darth Traya. Traitorous, someone who knows and understands Betrayal, honestly this is one of my favorite Darth names, and it helps that it belongs to my all time favorite SW character.
Darth Vader. How can no one have this on their lists? the original badass and the guy who basically made Darth a thing. Gotta have the classics. 🙂