We look after a mixed fleet of boeings and airbuses, mainly 320/1 /757/767 and theres not a lot between them TBH, both have there bad points of course, the 320 i would say if there is a weak area its the air con/ bleed system, we get a bit of trouble with sensors, flow valves, bleed valves, etc also flight control computers can give a few problems, however on the whole there good reliable aircraft, and quite user friendly from a engineers perspective