Bermuda's preshow wasn't good, but it did set up the ride really well. Toons was almost the exact opposite. Good preshow and made you feel like you were on an adventure, but didn't make a ton of sense.
The best is EASISLY the original Batman preshow. If you scrapped the simulators and just put a few extra 'In cave' effects you actually could potentially have had a fully satisfying attraction just with that. If Batman Adventure: The Preshow was at Fox Studios it would have been the headline attraction.
Second place to Gremlins, honestly it was almost 2 stand alone attractions in one there.
Worst would easily be Lethal Weapon. Giant Drop's was also shit, but also went for all of 20 seconds, so hard to be mad at it. Similar story for Wild Wild West's original preshow.
Also not a preshow as such, but the whole ToT thing was strange and unnecessary. I guess it gave a good chance for anticipation to grow but the whole attempt at a story was woeful. On the flipside, again, also not a preshow, but the walk through the wave on Wipeout always got me super pumped as a kid, and even waiting in there was really exciting for some reason.
EDIT:
Also not an Australian park, but the preshow for Hex at Alton Towers is phenomenal.