Both are probably about equal. Obi-Wan's fight with Maul was just as astounding as Anakin's fight with Dooku. The difference is that Dooku was a much more difficult opponent. Then again, Obi-Wan won his fight.
In the end, I'd say Anakin would probably win. He'd give into his anger much more easily than Obi-Wan would and probably begin to overpower Obi-Wan. This is TPM Obi-Wan too so he doesn't know Soresu yet so he doesn't have his tire-the-opponent-out strategy like he did to Anakin in Episode III. Obi-Wan would be countering Anakin's Shien with Ataru and in the end, lose to it.
They're probably even in the Force - Obi-Wan did Force Push numerous times in Episode I as well as Force Speed and Jump. Anakin showed his mastery in the Force in the steam room on Geonosis and a great Force sense by jumping from his car onto Zam's speeder. Anakin has a much greater latent Force potential though.
It'd be a long and hard fight but I'd say Anakin. He'd just overpower him. Sad to say because Obi-Wan is by far my favorite character but I hate being bias. Great fight though. XD