I'm going for Australia, although Haydos and Gilly have never really done much in 20/20 there is always time, plus they are so strond down the order with players like Punter, Mr Cricket, Simmo, Pup, ect.
My only concern is the bowling, but if Binga can start bowling 95mph yorkers at the end then he could be a handful, Mitch Johnson seems to have more control, and Stuart Clark is fairly reliable.
But 20/20 is more of a lottery than any other form of cricket and I think it will be settled more on the day than anything else.
Depends on how you bowl though.
Length balls are generally just smashed which is why you see more slower balls and yorkers bowled especially toward the end.
I do agree that the slower bowlers will be the best option as the batsman has to force the pace of the ball, but you could bowl underarm to the likes of Jayasuria, Gayle, Gilchrist, Pieterson ect and they could still smash it for miles.
Tough one to call as most Countries have the ability to score large, and rip the ball, but it's Gonna be the Aussies IMO, I think England YES England have a outside chance too, can't wait for the first game later )