Scott Hamilton just posted an article comparing the narrowbody market share of Airbus and Boeing, also comparing the subtypes. One aspect that is always missing when the backlogs of the A320neo and the B737MAX are compared is that the neo will be on the market two years earlier and what that means for "early availability".
Airbus and Boeing will both produce about 42 narrowbody aircraft a month when the reengined aircraft come to market. That means both will produce roughly 480-500 narrowbodies a year. That being said and assumed that the ramp up from the first production model to full production of the new model will be at the same pace at both manufacturers means that Airbus has an (at least theoretical) "early availability" advantage for the A320neo as long as the backlog is not between 960-1000 aircraft larger than that of the B737MAX. In detail that depends on the exact delivery dates for the individual airline customers, of course.
Right now Airbus has 2,068 firm orders, but counting the orders from Turkish Airlines and Lufthansa, which will probably be firmed up in the next weeks, there will be 2,198 firm orders.
Boeing meanwhile counts 1,185 firm orders for the B737MAX, so the difference is just about two years of full production now and in theory there is no "early availability" advantage for Airbus anymore. Let's see where the difference is after the Paris Air Show in June.