I know they haven't taken their chances at this stage in previous competitions, but I'd have to say the Waratahs are the team with the form and momentum and will be tough to beat.
My only concern for them is that they won't benefit from the week off they have earned by winning the round robin. It would usually be ideal to reach the end of the knock-out rounds and have that rest period, but of course, every side had three weeks off in June. That international window is a serious blight on the competition and I'm not sure that it is an advantage to be given the next round off.
But that said, the Waratahs have come across some form and they are going to have home advantage.