Yes historically speaking Qantas is the safest, but looking at the current global environment I wouldn't be looking at safety based on maintenance and history alone.
is the flag carrier for a state whose current government unquestioningly backs the Bush regime's view on how the world should be. This view is not shared by most of the world and exposes Qantas, as a flag-carrier, to targeting by those who wish to make an example of Australia's political perspective. The will of such groups has already been demonstrated against the Australian state in Bali. U.S. airlines, as we all know, have felt this same wrath.
For the same reason, I would choose to never fly El-Al.
What is a safe airline? What is a safe state?
I like flying airlines from small minority states that have good maintenance and service records. Air New Zealand, Polynesian, Air Tahiti Nui are all good from this end of the world.
If you're going to be big brother, accept the responsibilities that come with it.