I voted Dooku, but then I think Grevious may be a more logical choice.

"Grievous, those battle droids are expensive. The Jedi are never that harsh with their clones."

Personally, I voted with the count's last scene in mind in TROS.

Either the guy who disliked that the jedi werebstrying from the original path or a war criminal who attacks hospitals

Oh wait sorry

Dooku seemed to have more compassion while Grievous was more evil

Canon books, especially Dark Disciple, feature a relentless, hateful, tortuous Dooku. I always saw Grievous portrayed much more as a pawn in the larger picture. An angry, pouty, controllable child that Dooku manipulated exactly to his liking.

Dooku’s “compassion” is a guise. He’s evil, thirsts for power, and knows he must lie, cheat, and kill to get it.

Dooku loses his sympathetic factors and extremist goals come TCW and becomes far more ruthless and cruel, so both of those characters are equally as evil. But unlike Grievous, Dooku still occasionally shows some redeeming qualities such as remorse, loyalty and honor.