MD-81 - Max speed 925km/h (500kt), long range cruising speed 813km/h (440kt). Range with 155 passengers and reserves 2897km (1564nm).
A319- Range at 64 tonne (141,095lb) takeoff weight 3391km. High density single class layout can seat 142 passengers.
A320-200 - Max cruising speed 903km/h (487kt) at 28,000ft, economical cruising speed 840km/h (454kt) at 37,000ft. Range with 150 passengers and reserves with CFM56s 4843km (2615nm)
The only other ideal equivalent for the MD
-80 seems to be an Airbus aircraft, either the A320 or A319, depending on the load factors of the aircraft. However, as the A320 was created as a competitor for the 737, then wouldn't the 737 also be a competitor? Then, once again the question stands, why havn't the airlines operating the MD
-80 chosen the 737 as the replacement aircraft? Maybe the airlines were going to but financial struggles after the terrorist attacks diverted their attention, from replacing old aircraft to trying to keep the airline afloat.