Qui-Gon.
More experience.
Stronger physical fighter.
Plus he has the benefit of knowing Kenobi well, and is also his master. Kenobi won't fight that pissed against his mentor and friend. That's just plain Out of Character.
Besides we've all learned that the most dangerous version of Obi-Wan is when he is focused and in control.
Not to mention Kenobi looked like what he was during the Duel of Fates, an apprentice. He was the one getting constantly knocked down and split from the fight, not Qui-Gon.