FL has very high seniority. No growth there. Fully staffed. I wouldn't expect to ever be able to hold FL if you were hired today.
The seasonality means the Carib is junior in winter and senior in summer. There was one unfilled line in STX on the latest bid, so I guess you could say it is more junior.
The EAS routes out of ALB, PLB, SLK, & RUT will probably be available to junior pilots in the fall/winter this year. Otherwise its a move to the Carib. HYA & BOS will only have enough flying for a very few senior pilots.