Kavar, most likely. Or Vandar. Vandar is sneaky, small, and (if Yoda is any indication) tough as nails. Kavar is a standard Guardian/Weapons Master tank.
Dorak is probably rather good with force powers. I'm guessing he's a classic Consular, lots of Force abilities, but on the lower end for saber skills.
Atris - her mental instability would likely cause her to make a critical error.
Zhar is a well-rounded Sentinel, but is likely to get nailed by those in specialty. Zez-Kai? I'd like to see him in his prime, because the fellow we see on Nar Shadaa didn't seem to have any fight left in him. Vash we just didn't see enough of, but from what little we did see, she's not as tough as she is smart. She almost had a way out of the Korriban academy before getting abruptly halted by Sleeps-With-Vibroblades
Vrook - tough bastard. He'll make it to the finals on sheer stubborn.