Comparing American and Australian political leaders

In PMs and presidents: in another leader's shoes the always interesting Greg Jericho looks at how various USA presidents might fare in Australian politics and how our Prime Ministers might have gone in the US system.

In his "Plácido Domingo speech" in 1990, Paul Keating argued that Australia had never had a great leader of the stature of an Abraham Lincoln, a Franklin Roosevelt or a Winston Churchill. Whether this is accurate is one for historians to debate, but of those three only Churchill comes out of the Westminster system. When observing the current candidates and the past US presidents and past Australian prime ministers, I wonder which nation and which democratic process ends up with the better leaders, and perhaps more interestingly, which leaders from one country would rise to the top in the other country's democratic system?