Hi leo38.
I am afraid it is heart versus head time. You have identified the points faitly well I think, but to expand on them: The Alfa is the choice on looks, drive and just overall coolness. The Audi for resale value and "percieved quality". The VW for bargain high quality (if rather dull) drive.
The Alfa's value will drop like a stone, although most nagging worries regarding build quality have been rectified. It all depends what you want I suppose. The ownership experience or the resale value?
Maybe another option is to buy a nearly new 159, you would be surprised how much depreciating it has already done.