Audi go for Audi! Especially because of Toyota's recalls. You never know when you'll see another recall! Not saying Toyota is bad, just saying it's rather safe then sorry. Lol, to me its the A5-better horsepower rating.
You cant wrong with either model. If money isn't the issue then i would go with the A5. Ive been in the car and its just a great ride...just a little pricey and the gas isn't as great as the IS250.