Lord Lucien
Lets all love Lain
The RotS novel as seen from Dooku's perspective has Anakin go through three separate mental phases in their duel. After Dooku stops fooling around and knocks out Kenobi, Anakin becomes angry and starts legitimately pushing him back--that's "Angry Anakin". Dooku uses Dun Moch, taunting Anakin to "use his anger, something no Jedi would do" (to paraphrase), prompting Anakin to shy away from and repress his anger---that's "Jedi Anakin". Eventually he turns Super Saiyan and brings Dooku down in seconds---"Zone Anakin".
To an extent that interferes with what we see in the film, and I don't know where canon policy officially stands on stuff like that. Suffice to say, the greatest extrapolation we have of characters' fighting prowess comes from this source.
But thanks to the scene jumping of the film, and the writing in the novel, the Anakin vs. Obi-Wan duel isn't as victim to such inconsistencies. Twice before I've quoted whole passages from the book, so I refuse to do it again. To sum it up, "Vader-Anakin" was giving Obi-Wan hell (from Obi-Wan's perspective no less) and showed no signs of fatigue. He showed such power and skill in their fight that Obi-Wan had to scrape the bottom of his Barrel of Tricks just to stay alive. My wording, not his.
Zonakin is the clear-as-bell, uninhibited, "perfect" Anakin. Vader is the relentless powerhouse of emotion, but lacks the clarity of focus, which would have killed Kenobi not too long in to their duel. But lacking that, and given Kenobi's bonus of familiarity, he lived.