Well it was only a taste of their times on Idol, and obviously they've all improved by leaps and bounds since then (some of these are nearly 20 years old hahaha).
Paulini, who came 4th in Season 1, was the only one of the Divas to never receive a critique about her vocals (Dicko, one of the judges, in fact said they didn't ever feel the need to) but did receive a rather nasty critique (that made massive news headlines here) about a gold dress:
Ricki-Lee was the hot favourite of Season 2, being described as the "party invite". She was criticised for a modern interpretation of "We Can Work It Out" on the Beatles night. Although it was still pretty good, the Australian public got very complacent and simply didn't vote for her, thinking she'd be safe. She came 7th, and is considered the most robbed contestant of any season of Australian Idol.
Emily Williams was generally considered the best vocallist of Season 3, receiving several "Touchdowns" (which in Australian Idol was the highest form of praise that could be given by a judge). Sadly she choked on the final 2 night and was pipped at the post.
(Can't find any of her top 2 performances).
Kate DeAraugo was the surprise winner of Season 3, having gotten through the competition by not ever being the best (until Final 2), just by never being the worst.
Jess Mauboy was the runner up of Season 4. At just 16 when she entered, she proved to be a powerhouse, but was hampered by her lack of experience, with the public ultimately voting for a far superior (at the time) vocallist.