I was always more excited for Heavy Rain than I was for Alan Wake but I thought Alan Wake outselling Heavy Rain was as close to a sure thing as possible. I mean 360 games tend to sell more than PS3 games. Alan Wake was more tried and true than Heavy Rain's experimental style. Heavy Rain didn't seem to have a built in audience and seemed like it would be a niche game (which is fine. I like "niche".) I definitely put my money on Alan Wake.
Just goes to show that anything can happen in the WWE. People were starving for something unique, I guess. Heavy Rain beat Alan Wake commercially and critically. And as an owner of both games, Heavy Rain deserved it.
So when we discuss Halo vs Gran Turismo (I still don't know why.), Move vs. Kinect, or PS3's vs. 360's, we do so with an air of uncertainty. Half of the guys in the argument are going to be right. Half of them are going to be wrong. That's just how it goes. But if things were 100% guaranteed, what would be the fun in the debate?