The A3 is more...cute I would say, but it is not original at all, already seen, so copy-pasted it is boring. Too bad. The rear is too massive, also.
So 1er, by a great margin.
Still hate the ridiculously too big front lights of the 1er, not a fan of its banana-like side profile, and the rear is not really well integrated to the rest of the car...Or is it the front which does not go with the back?
But the car is more original, does not look like a sedan with cutted-roof, and just appeals much more to me. The 1er just wants you to open the roof and drive in the sun, with its cool low side line and low back end.
The A3 has a rear that is too short, too high, too massive, the sideline too high, and the rear protective archs are just so badly integrated...