I can only speak for UNSW but if you attend one of their information sessions, they do seem to emphasise that their graduates wind up in the CX cadet program, RAAF and Qantas Link.
I have three friends who are doing the course and they are enjoying it. I would personally still stay away from the aviation degree though, which I know has been discussed quite a lot. Don't get me wrong though, I would say that in the future, having a degree will be important.
Also, I think limiting your scope to just cadet programs isn't the best of ideas. You also have to take into account your long term goals and thinking about which degree will get you into a cadet program probably isn't the best way to go. I'll use myself as an example. I got accepted into ADFA as a RAAF Pilot last year for 2011, but with the degrees they offered, it didn't align with my long term goals. Sure, you may want to stay in aviation for the rest of your life, but considering the state in which Qantas is, it's probably best to have some kind of degree non-aviation related.
This is just my opinion though. Go with whatever you want to pursue.