my guess is you want same day commuting, the goal being late reports on day 1 and early release on day 3 or 4 for travel back and forth to BOS when you get a line. Sounds like the 88 will give you that seniority the fastest plus slightly better trips than the a320? The 73 will be the most senior of the 3 with the best trips, but you'd probably be commuting in the night before for quite a while to sit reserve.