so whats your list?
To be quite honest, I'm still sort of thinking on it.
Some inclusions off the top of my head would definitely be Gillard. She did have a frustrating way of speaking at times, but she was a much clearer communicator than Rudd and than Abbott, despite her extremely frustrating accent and voice (and pronunciation of initiate). Misogyny speech was a fairly good example of a speech done well, particularly for a speech given extempore (to some extent).
Keating was absolutely hopeless with paper in front of him (and was blessed with an absolutely fantastic speech writer for Redfern, despite what he says), but some of his extempore exchanges in parliament were incredible. He made mince meat of Hewson, Howard and Downer (this was actually why I criticised Downer as a choice—for the most part he was quite good, but there's a good example of Keating tearing shreds off him that was just too good to pass up).
Howard certainly had his moments too, but suffered Gillard disorder. For the most part he was a whining pain in the neck, but there are certainly some good examples of when Howard really shone, particularly when he came out with "we will decide who comes to this nation and the circumstances in which they come". Despite really hating that line for its effect, it was a fantastic moment in oratory in Australia—a very powerful moment.