Dooku radiates coolness. A nice change from your usual raging sith not to mention Christopher Lee! Plus you can't beat his beard or outfit. He is a big naughty sometimes, but I blame Christie Golden for that.
Kenobi is one of the most chill jedi out there next to Shaak Tii in TCW. His beard rivals Dooku's.
Sidious is alright as is Anakin; they have their cool moments but sometimes fall flat in terms of character.
Most of the other sith are too "emotional" to make my cool list.
...and how can I forget Mace motherf***ing Windu?