I would go to ASA. If you are hired by ASA, you will be based in ATL (it is their only base). No wild cards.

Both Skywest and Republic have ATL bases. Both of these airlines are considered slightly better than ASA, but there is a good chance you will not be based in ATL. Skywest is only hiring for the EMB, and that means west coast for atleast one year. Republic may put you on the Chataqua certificate (meaning 50 seaters), and thus you will not be able to bid ATL until you are able to change equipment (and I believe Republic has a seat lock).

ASA is a good regional. They are not one of the best (IMO), but they are probably the best choice for you. Skywest or Republic should probably be your 2nd choices.