I say neither for these reasons:
I believe Abbot has the qualities for an Opposition leader - criticise the government, point out what's wrong with it, and try to get them to make a form of compromise. I do not see him as having the potential for the leader of this country. His lack of clear policy in many areas is example of this.
Rudd, on the other hand, has promised so much to this country and failed to deliver on a number of these promises. His ineffectiveness at Copenhagen can almost be forgiven only because the European leaders were undermined in a similar kind of way. But... I have looked at what Rudd's done and I don't believe I want him in charge either.