I'm not sure what Kenobi and Jinn would be able to do against Traya's drain at full-power at a potent DS nexus, tbh.
The only way in which they would be able to win is by speedblitzing these two. With Sion there, however, it's doubtful that they'd be able to take them out quick without being drained first.
Traya is obviously superior to Obi-Wan in the Force, but she'd probably lose in a lightsaber duel so it really depends on whether Obi-Wan can close the distance before Traya overwhelms him. I say it can go either way, with me leaning towards Traya.
Sion beats Qui-Gon. Unlike Jinn, he can die as many times as he wants to. Sion has taken down numerous Jedi throughout his career and "died" only to rise again.
His quasi-immortality is what will allow him to win. And experience of course.