I think the Aussies will win for a number of reasons. Firstly, they came so close to winning last year in English conditions favouring the English bowlers, and I think Australian conditions will give the Aussies an advantage, which, when combined with all the other advantages the Australians have over the English, will prove too big an advantage and difference for the English to win.
Secondly, the English have some injury concerns, and many changes to the line up, which could affect their team performance. Then again, it might not, though that is unlikely, no team can ever perform the same way as they have done previously.
All of this combined (there are more but I just can't be bothered to type them up now; had some late nights, having an early one tonight...) give me the opinion that the Aussies will convincingly regain the Ashes in Australia.