What makes a great magazine cover?

What makes a great magazine cover? Of course art and what catches the eye is most often purely subjective but there are some basic principles. Australian Creative is known for unusual and quirky covers, a tradition we hope to continue with an even bolder look in our next issue.
 
While I'm a little young to have been their demographic, Richard Neville and Martin Sharp's Oz magazine shook both sides of globe with their bold and irreverent cover art. As a young would-be journalist in the late 1980s, Oz was the stuff of myth and legend.

I remain after all these years an unashamed fan of both Neville and Sharp so it was with extreme delight I learned the news of the high grade print re-issue of some of their most famous covers. There are no current plans for an exhibition although with the right lobbying one never knows.
 
We will speak with Neville in the near future exploring the topic further in print, but for now, we want to hear from YOU.
What makes you pick up a magazine? Is it beauty, intrigue, curiosity, habit? Ought covers to be safe so as not to offend, or confronting so they challenge?
Do aesthetic drivers manifest in financial results or is the art and business of magazines a perennially fraught balance?

It's just advertising, right?

We want to know what YOU think makes a great cover. Please comment on this story and tell us what you think.