The latest fleet count has UAL adding 14 737's and 9 A319's in 2016. So it looks like either airplane would be a great growth airplane to be in (shortest time on reserve).
With the added 737-700's coming in mid 2017 and used Airbuses, its a good time to be a United pilot/new-hire again.
Looks like guys with only a few years are holding wide body FO as well (in ORD & EWR). Let the good times roll.