If its just between the two : Id take the A3. I've never owned an Audi but have owned several beemers. So even though I am partial to BMWs, that AUDI DSG transmission + Quattro + more HP = more fun. Though you must do a test drive to make sure you're spending your millions well
But, if you can wait, personally, Id get the 335i (I saw a silver one yesterday blasting UP the rockwell ramp from EDSA).... killer killer killer speed. He was at a standstill in traffic, made the lane switch to the left, floored it and I heard the sweet sound of its 6 cylinder and forced induction turbines .... super impressive . A 335d would even be better!!!! I heard a rumour that they are releasing the new twin-turbo 325d or 323(?)d diesel engines next year. 200 bhp and 400+NM of torque. Might wanna wait for those small monsters!