Jedi Dooku is confirmed to have only been surpassed by Mace and Yoda in Jedi history (up to AotC) as a swordsman. That includes Revan in KotOR. And Sith Dooku is confirmed to have increased his skills in dueling, so he's factually above KotOR Revan as a swordsman.
The Obi-Wan part was because Neph somehow thought I said that Obi-Wan was factually better than Revan, which I never did.
Yoda taught many pupils throughout his years, including Dooku, who became one of the finest sword masters the Order ever produced - eclipsed only by Mace Windu and Yoda himself.-- The Official Starships & Vehicles Collection #48
And:
However, once Dooku left the Jedi Order to become an apprentice to the Sith Lord Darth Sidious, his skills became even more formidable.-- The Official Star Wars Fact File #68