You're all forgetting a very important thing, HATE fuels the darkside, or a similar very strong emotion, Maul had this, Dooku was cranky at best, he was not definately filled with hate, maybe disdain, but I hardly
consider disdain dark side fuel. The fact that Dooku had been a jedi, hampered him in fully realizing his power and potential. He was far more concerned with theatrics and showing his superioity to his opponets. (He was reference as to admiring his lack of use of hand gestures for using the force that the jedi used in the labyrinth of evil book I believe) This made him prone to toying with his opponents to display his supirioity, while the only thing Maul was concerned with was doing his job and pleasing his master. In this one Maul wins, one does not TOY woy maul and live. Obi Wan won the battle because he was not trying to show he was better he just WAS better. Dooku lacks the sheer ruthlessness to be a real sith, he was never anything more than a pawn, which don't get me wrong Maul was the same just a better and more useful, ALSO Maul was more adept at stealth the Dooku