FR8,
Ill try to answer this question without being a dbag... ATL is more senior however it's the CRJ sides largest base. Right now the CRJ side seems to be hiring about 20 per month. ATL is more senior but in general you may be able to get it right out of class or within a few months. It is more likely that you will be able to get better schedules due to increased relative seniority at other bases (DTW, DFW, IAD).
That said, don't come here. Go to compass. Your upgrade will be about a year... who knows what's going to happen to ASA/XJT... We are in for a battle and we just told management to go kick rocks ( soooo frickin proud of my fellow pilots)... anyways, I'm just trying to say it is a negative environment that you may not enjoy. If you want to be here then we welcome you with open arms, just don't say you weren't warned...