I would definately get the Audi S5. The Audi S5 looks much better. It has AWD and if you are talking about the new 2008 BMW M3, then the Audi S5 is also much weaker, but just as fast with only a 0.1 difference in 0-60 time and the same top speed. The Audi S5 is also newer technology since it came out after the M3. The Audi S5 is cheaper to buy, but the maintemance costs are higher than the BMW's.