hmm
Siding with Ulic and Koon. I've been re-assessing how I view Kenobi as a fighter and I've come to the conclusion that in a no-circumstances, straight duel, he'll probably end up losing against someone like Ulic who rivals him in skill. Pretty much because of Soresu's dedication to defence, with it's offence lying in tiring out the opponent or having them slip up. When you're talking about opponents of Ulic's caliber, who have boundless stamina and tend not to make any silly mistakes, it's hard to picture Kenobi pulling much off, and then Ulic's application of Djem So still leaves him with offensive options at the end of the day. It could arguably be a stalemate but if you have to pick someone who is going to die at the end of the day, it should be Kenobi.
Kenobi's wins over the likes of Maul during TPM, Savage on Florrum, Grievous and Anakin during RotS and so on, are all victories littered with specific circumstances that allowed Kenobi to come out with the win. When we've seen him take on opponents without any special aid or advantage, he's either stalemated them inconclusively or lost (Maul, Ventress, Grievous etc) whereas all of these people have legitimate wins on their record at some point or another. If not for his fighting style allowing him to seriously prolong fights, and his own immense skill, Kenobi would likely lose to those three (although he ended up beating Grievous once he worked out how to make Soresu work to his advantage against the multiple blades. He's taken numerous losses from Grievous, though).
Zallow and Koon are the weaker combatants. I don't think there's a lot to split them aside from a power advantage on Koon's part.