ATR guys have seniority?! That’s interesting! My mates there are all complaining that their seniority is worthless as the company intends to take direct entry to both the 737 and 777 over the top of them.
If you are desperate for a VA gig take the ATR and expect anywhere from 5 to 10 years. I think you’d be better off waiting and getting some decent multicrew turboprop time and going to the jet rather than the leper fleet.