Looks are very subjective. We looked at a similar range to those, and we (The Mrs and I) both preferred the BMW 1 Series. I think that A3's are a bit of a bland box on the Outside. Interior, we both preferred the A3 (and it has a fair bit more space). Drive and Handling the 1 series.
Power wise, the 118D felt adequate, the 120D feels (and is) much quicker.
Overall the extra economy of the 1 Series due to the Efficient dynamics swung it, and we ended up in a used 07 120D M Sport, as for the 2 of us there is plenty of room.
You are buying new though, and personally If I went that way, I would be tempted to to spec up a 118D rather than paying the extra for the 120D.