Two other things to consider:
You said the 128i has NO options. No sport package? That's a no-go for the 1 series. The seats suck, and the 128i will have a very soft suspension.
As for the A5... is it turbo? Audi turbo engines has terrible carbon buildup problems... even more so than the 135i engines. You'd be adopting the car around the mileage that those problems might just be beginning to rear their heads. Other than that, it's beautiful, luxurious, but just doesn't drive as well as a 1 series.
Both options don't sound ideal (to me). I would find a sport package 128i and some snow tires, or a 328xi (it's big and boat-like, just like the Audi, though).