All in all the Airbus is more comfortable both up front and in the back. The cabin seems to be a shade wider in the back. This is just my observation.

Having been in the Airbus I would say it has its ups and downs. My only experience in the 73's is riding up front. The 73 is still much more a pilots stick and rudder airplane and always will be.

As for economics i am guessing it is a draw. The 737's might be a shade more efficient especially with the winglets on them.

I am not sure but didnt Airbus offer the 320s at a lower cost for a while with sooner deliveries. This may be a draw that makes an airline choose one or the other. (Companies like SWA have soaked up a lot of the deliveries the last 5 years)

Really I think it comes down to are you a Boeing person or a Bus guy/gal.